The periodic table: symbols, atomic numbers and atomic weights

All named chemical elements with their symbols, atomic numbers, standard atomic weights (IUPAC 2021), periods, groups and blocks, cross-checked in two sources.

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The periodic table of elements
Element	Period	Symbol	Atomic number	Standard atomic weight	Period	Group	Block
Hydrogen	Period 1	H Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	1 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	1.008 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Helium	Period 1	He Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4.002602 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	18 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Lithium	Period 2	Li Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6.94 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Beryllium	Period 2	Be Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	9.01218 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Boron	Period 2	B Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	10.81 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	13 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Carbon	Period 2	C Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	12.011 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	14 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Nitrogen	Period 2	N Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	7 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	14.007 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	15 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Oxygen	Period 2	O Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	8 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	15.999 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	16 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Fluorine	Period 2	F Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	9 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	18.9984032 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	17 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Neon	Period 2	Ne Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	10 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	20.1797 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	18 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Sodium	Period 3	Na Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	11 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	22.98976928 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Magnesium	Period 3	Mg Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	12 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	24.305 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Aluminumalso spelled Aluminium	Period 3	Al Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	13 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	26.98154 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	13 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Silicon	Period 3	Si Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	14 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	28.085 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	14 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Phosphorus	Period 3	P Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	15 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	30.973762 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	15 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Sulfur	Period 3	S Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	16 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	32.06 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	16 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Chlorine	Period 3	Cl Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	17 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	35.45 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	17 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Argon	Period 3	Ar Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	18 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	39.95 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	18 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Potassium	Period 4	K Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	19 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	39.0983 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Calcium	Period 4	Ca Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	20 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	40.078 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Scandium	Period 4	Sc Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	21 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	44.95591 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Titanium	Period 4	Ti Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	22 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	47.867 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Vanadium	Period 4	V Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	23 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	50.9415 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Chromium	Period 4	Cr Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	24 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	51.9961 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Manganese	Period 4	Mn Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	25 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	54.9380 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Iron	Period 4	Fe Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	26 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	55.845 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Cobalt	Period 4	Co Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	27 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	58.93319 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	9 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Nickel	Period 4	Ni Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	28 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	58.6934 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	10 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Copper	Period 4	Cu Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	29 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	63.546 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	11 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Zinc	Period 4	Zn Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	30 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	65.38 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	12 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Gallium	Period 4	Ga Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	31 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	69.723 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	13 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Germanium	Period 4	Ge Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	32 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	72.630 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	14 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Arsenic	Period 4	As Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	33 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	74.9216 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	15 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Selenium	Period 4	Se Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	34 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	79.0 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	16 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Bromine	Period 4	Br Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	35 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	79.904 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	17 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Krypton	Period 4	Kr Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	36 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	83.798 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	18 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Rubidium	Period 5	Rb Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	37 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	85.4678 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Strontium	Period 5	Sr Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	38 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	87.62 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Yttrium	Period 5	Y Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	39 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	88.906 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Zirconium	Period 5	Zr Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	40 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	91.224 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Niobium	Period 5	Nb Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	41 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	92.9064 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Molybdenum	Period 5	Mo Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	42 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	96.0 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Technetium	Period 5	Tc Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	43 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Ruthenium	Period 5	Ru Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	44 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	101.07 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Rhodium	Period 5	Rh Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	45 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	102.9055 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	9 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Palladium	Period 5	Pd Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	46 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	106.42 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	10 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Silver	Period 5	Ag Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	47 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	107.8682 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	11 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Cadmium	Period 5	Cd Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	48 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	112.41 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	12 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Indium	Period 5	In Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	49 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	114.818 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	13 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Tin	Period 5	Sn Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	50 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	118.710 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	14 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Antimony	Period 5	Sb Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	51 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	121.760 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	15 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Tellurium	Period 5	Te Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	52 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	127.60 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	16 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Iodine	Period 5	I Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	53 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	126.90447 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	17 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Xenon	Period 5	Xe Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	54 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	131.293 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	18 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Cesiumalso spelled Caesium	Period 6	Cs Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	55 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	132.905452 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Barium	Period 6	Ba Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	56 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	137.327 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Lanthanum	Period 6	La Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	57 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	138.90547 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Cerium	Period 6	Ce Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	58 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	140.116 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Praseodymium	Period 6	Pr Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	59 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	140.908 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Neodymium	Period 6	Nd Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	60 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	144.242 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Promethium	Period 6	Pm Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	61 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Samarium	Period 6	Sm Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	62 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	150.36 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Europium	Period 6	Eu Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	63 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	151.964 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Gadolinium	Period 6	Gd Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	64 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	157.25 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Terbium	Period 6	Tb Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	65 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	158.92535 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Dysprosium	Period 6	Dy Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	66 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	162.500 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Holmium	Period 6	Ho Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	67 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	164.9303 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Erbium	Period 6	Er Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	68 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	167.259 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Thulium	Period 6	Tm Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	69 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	168.9342 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Ytterbium	Period 6	Yb Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	70 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Lutetium	Period 6	Lu Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	71 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	174.9668 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Hafnium	Period 6	Hf Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	72 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	178.49 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Tantalum	Period 6	Ta Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	73 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	180.94788 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Tungsten	Period 6	W Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	74 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	183.84 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Rhenium	Period 6	Re Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	75 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	186.207 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Osmium	Period 6	Os Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	76 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	190.23 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Iridium	Period 6	Ir Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	77 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	192.217 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	9 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Platinum	Period 6	Pt Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	78 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	195.084 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	10 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Gold	Period 6	Au Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	79 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	196.96657 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	11 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Mercury	Period 6	Hg Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	80 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	200.592 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	12 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Thallium	Period 6	Tl Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	81 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	204.38 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	13 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Lead	Period 6	Pb Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	82 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	207.2 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	14 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Bismuth	Period 6	Bi Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	83 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	208.98040 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	15 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Polonium	Period 6	Po Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	84 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	16 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Astatine	Period 6	At Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	85 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	17 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Radon	Period 6	Rn Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	86 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	18 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Francium	Period 7	Fr Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	87 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Radium	Period 7	Ra Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	88 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	s Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Actinium	Period 7	Ac Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	89 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Thorium	Period 7	Th Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	90 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	232.038 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Protactinium	Period 7	Pa Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	91 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	231.03588 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Uranium	Period 7	U Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	92 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	238.02891 u Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Neptunium	Period 7	Np Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	93 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Plutonium	Period 7	Pu Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	94 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Americium	Period 7	Am Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	95 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Curium	Period 7	Cm Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	96 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Berkelium	Period 7	Bk Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	97 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	1 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Californium	Period 7	Cf Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	98 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	2 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Einsteinium	Period 7	Es Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	99 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	3 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Fermium	Period 7	Fm Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	100 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Mendelevium	Period 7	Md Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	101 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Nobelium	Period 7	No Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	102 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Lawrencium	Period 7	Lr Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	103 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	f Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Rutherfordium	Period 7	Rf Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	104 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	4 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Dubnium	Period 7	Db Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	105 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	5 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Seaborgium	Period 7	Sg Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	106 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	6 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Bohrium	Period 7	Bh Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	107 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Hassium	Period 7	Hs Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	108 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	8 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Meitnerium	Period 7	Mt Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	109 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	9 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Darmstadtium	Period 7	Ds Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	110 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	10 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Roentgenium	Period 7	Rg Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	111 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	11 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Copernicium	Period 7	Cn Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	112 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	12 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	d Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Flerovium	Period 7	Fl Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	114 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	14 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.
Livermorium	Period 7	Lv Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	116 Verified Source: IUPAC CIAAW standard atomic weights 2021 (via the periodictable package), retrieved 2026-10-26 · Blue Obelisk Data Repository, retrieved 2026-10-26 record 1 record 2Verified: Two independent sources agree (or the defining body published it and we read it directly).	—	7 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	16 Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.	p Sourced Source: Blue Obelisk Data Repository, retrieved 2026-10-26 recordSourced: From one named source with a reference.

Select a value to see its source and retrieval date. A dash means we found no reliable value, or the sources disagreed.

Sources and licences

IUPAC CIAAW standard atomic weights 2021 (via the periodictable package) — Public domain
Blue Obelisk Data Repository — CC0 1.0 (public domain dedication)

Data compiled 2026-10-26.