Atomic Element Z = 90 • Actinide
Thorium (Th) — Atomic Data, Electron Shells & Reactions
Thorium (symbol Th, atomic number 90) has a standard atomic weight of 232.04 u and ground-state configuration [Rn] 6d2 7s2.
Atomic Number (Z)
90
IUPAC Symbol
Th
Standard Atomic Weight
232.04 g/mol
Period / Group / Block
7 / f-block / f-block
Condensed Electron Config
[Rn] 6d2 7s2
Full Subshell Config
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 6d2 7s2
Principal Shell Occupancy
[2, 8, 18, 32, 18, 10, 2]
Pauling Electronegativity
1.3
First Ionization Energy
587 kJ/mol
Covalent Radius
206 pm
Melting Point
2115 K (1841.85 °C)
Boiling Point
5061 K (4787.85 °C)
Density
11.72 g/cm³
Oxidation States
+4
Th (Z=90) — Valence shell highlighted in vermilion