Thorium

Actinide · 232.038 u · group 3, period 7

Thorium · Th

Atomic number90

SymbolTh

CategoryActinide

Standard stateSolid

Group · Period · Block3 · 7 · f

Electron configuration[Rn]7s2 6d2

Atomic mass232.038 u

Atomic radius237 pm

Protons / Neutrons / Electrons90 / 142 / 90

Shells (e⁻ per shell)2, 8, 18, 32, 18, 10, 2

Electronegativity (Pauling)1.3

Ionization energy6.08 eV

Electron affinity—

Oxidation states+4

Melting point2.02e+3 K · 1.75e+3 °C

Boiling point5.06e+3 K · 4.79e+3 °C

Density11.72 g/cm³

Year discovered1828

CPK color

#00BAFF

State at room temp (25 °C)

solid

Position