Compare elements

Put any two or three elements side by side and see how their core properties line up — atomic mass, category, group and period, electron configuration, and when each was discovered. The greatest value in each numeric row is highlighted.

Element 1 Element 2 Element 3 (optional)

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	Fe Iron	Au Gold	O Oxygen
Atomic number	26	79	8
Symbol	Fe	Au	O
Atomic mass	55.845	196.97	15.999
Category	Transition metal	Transition metal	Reactive nonmetal
Group	8	11	16
Period	4	6	2
Phase at STP	Solid	Solid	Gas
Electron configuration	[Ar] 3d6 4s2	[Xe] 4f14 5d10 6s1	[He] 2s2 2p4
Discovered	Antiquity	Antiquity	1774
Notability	The most-used metal on Earth, the core of steel and of our own blood.	The prototypical precious metal, unreactive, conductive, and endlessly malleable.	The reactive gas animals breathe and the most abundant element in the Earth's crust.

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