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 |