Hydrogen vs Selenium
| Property | H Hydrogen | Se Selenium |
|---|---|---|
| Atomic number | 1 | 34 |
| Symbol | H | Se |
| Name | Hydrogen | Selenium |
| Category | nonmetal | nonmetal |
| Standard Atomic Weight | 1.007975 u | 78.971 u |
| Period | 1 | 4 |
| Group | 1 | 16 |
| Block | s | p |
| Phase at STP | gas | solid |
| Electron configuration | 1s1 | [Ar]4s23d104p4 |
| Oxidation states | [-1, 1] | [-2, -1, 0, 1, 2, 3, 4, 5, 6] |
| Electronegativity (Pauling) | 2.2 | 2.55 |
| Electron affinity | 0.75419 eV | 2.0206 eV |
| Density | 0.08988 kg/m³ | 4809 kg/m³ |
| Melting point | -259.34 °C | 220.5 °C |
| Boiling point | -252.87 °C | 684.85 °C |
| Discovery year | 1766 | 1817 |