Selenium
Nonmetal| Atomic number | 34 |
|---|---|
| Category | Nonmetal |
| Atomic mass | 78.971 |
| Electron configuration | [Ar]3d¹⁰ 4s² 4p⁴ |
| Oxidation states | −2, +4, +6 |
| Electronegativity | 2.55 |
| Melting point | 221 °C |
| Boiling point | 685 °C |
| Density | 4.81 g/cm³ |
| Crystal structure | Hexagonal |
| Group | 16 |
| Period | 4 |
| Block | p |
| Discovered | 1,817 |
| Crustal abundance | 0.05 ppm |