| Se | Selenium | Non-Metal |
| Atomic number: | 34 | Atomic weight: | 78.96 | ||
| Shells: | 2,8,18,6 | Orbitals: | [Ar] 3d10 4s2 4p4 | ||
| Melting point: | 217°C | Boiling point: | 684.9°C | ||
| Covalent radius: | 1.16 | Å | Atomic volume: | 16.45 | cm³/mol |
| Atomic radius: | 1.22 | Å | Ionic radius: | .50 (+4) | Å |
| Electronegativity: | 2.55 | Oxidation states: | -2,(4),6 | ||
| 1st ionization pot.: | 9.7524 | V | 2nd ionization pot.: | 21.19 | V |
| 3rd ionization pot.: | 30.82 | V | Specific heat: | 0.32 | J/gK |
| Heat of fusion: | 6.694 | kJ/mol | Heat of vapor.: | 37.70 | kJ/mol |
| Thermal conduct.: | 0.0204 | W/cmK | Electrical conduct.: | 1.0e-12 | 10^6/cm ohm |
| Density: | 4.79 | g/cm³ | Valence: | -2,4,6 |