Thorium

Actinide · atomic number 90

90232.03774ThThoriumSolidActinide

Thorium is a chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only two significantly radioactive elements that still occur naturally in large quantities as a primordial element (the other being uranium). It was discovered in 1828 by the Norwegian Reverend and amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jakob Berzelius, who named it after Thor, the Norse god of thunder.

Properties of Thorium

Element category	Actinide
Atomic number	90
Atomic mass	232.03774 u
Phase at STP	Solid
Group	3
Period	7
Block	f
Electron configuration	[Rn] 6d2 7s2
Electrons per shell	2, 8, 18, 32, 18, 10, 2
Electronegativity (Pauling)	1.3
Melting point	2023 K (1750 °C)
Boiling point	5061 K (4788 °C)
Density	11.724 g/cm3
Discovered by	Jöns Jakob Berzelius

← Actinium · Periodic table · Protactinium → Pa

About the actinide group

Mostly radioactive, heavy metals — several made only in reactors — whose fission powers nuclear energy and weapons.

Data: Periodic-Table-JSON (CC BY-SA 3.0) · stored statically on our server. https://en.wikipedia.org/wiki/Thorium

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11 elements: Elements that readily gain or share electrons — the building blocks of water, air, living tissue and most organic chemistry.

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15 elements: Mostly radioactive, heavy metals — several made only in reactors — whose fission powers nuclear energy and weapons.

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