| Element | Selenium | Symbol | Se |
| Atomic Number | 34 | Molar Mass | 78.96 gmol-1 |
| Electron Configuration | [Ar]3d104s24p4 | Normal State | solid nonmetal |
| Density @STP | 4.81 g cm-3 | Melting Point | 221oC |
| Boiling Point | 685oC | Stable Isotopes | 74Se, 76Se, 77Se, 78Se, 80Se, 82Se |
| Atomic Radius | 117 pm | Ionic Radius | 198 (2-) pm |
| Electronegativity (Pauling) | 2.55 | Ionization Energy (1st) | 941 kJ mol-1 |
| Ionization Energy (2nd) | 2044 kJ mol-1 | Ionization Energy (3rd) | 2974 kJ mol-1 |
| Molar Heat Capacity | 25.4 J K-1mol-1 | Standard Molar Entropy | 42.4 J K-1mol-1 |
| Enthalpy of Fusion | 5.1 kJ mol-1 | Enthalpy of Vapourization | 26.32 kJ mol-1 |