Stable isotope Thorium (Th)

Isotope Atomic Mass Half-life Mode of Decay Nuclear Spin Nuclear Magnetic Moment
Th-227 227.027699 18.72 days α to Ra-223 3/2 No data available
Th-228 228.028731 1.913 years α to Ra-224; O-20 0 No data available
Th-229 229.031754 7900 years α to Ra-225 5/2 0.46
Th-230 230.033126 75,400 years α to Ra-226; SF 0 No data available
Th-231 231.036296 1.063 days α to Ra227; β- to Pa-231 5/2 No data available
Th-232 232.0380508 1.40 x 1010 years α to Ra-228; SF 0 No data available
Th-233 233.041576 22.30 minutes β- to Pa-233 1/2 No data available
Th-234 234.036596 24.10 days β- to Pa-234 0 No data available

Properties of Thorium

Name Thorium
Symbol Th
Atomic number 90
Atomic weight 232.03806
Standard state Solid at 298 ºK
CAS Registry ID 7440-29-1
Group in periodic table N/A
Group name Actinoid
Period in periodic table 7 (Actinoid)
Block in periodic table f-block
Color Silvery white
Classification Metallic
Melting point 1750 °C
Boiling point 4820 °C
Vaporization point 4788 °C
Thermal conductivity 54 W/(m·K)
Electrical resistivity 15 x 10-8 Ω·m
Electronegativity 1.3
Specific heat 0.13 kJ/kg K
Heat of vaporization 530 kJ·mol-1
Heat of fusion 16 kJ·mol-1
Density of solid 11.72 g/cm3
Electron configuration [Rn]6d27s2
Atomic radius 1.80 Å
Ionic radius Th4+: 1.05 Å (coordination number 8)
Most stable oxidation state +4