Chlorine vs Selenium
| Property | Cl Chlorine | Se Selenium |
|---|---|---|
| Atomic number | 17 | 34 |
| Symbol | Cl | Se |
| Name | Chlorine | Selenium |
| Category | halogen | nonmetal |
| Standard Atomic Weight | 35.4515 u | 78.971 u |
| Period | 3 | 4 |
| Group | 17 | 16 |
| Block | p | p |
| Phase at STP | gas | solid |
| Electron configuration | [Ne]3s23p5 | [Ar]4s23d104p4 |
| Oxidation states | [-1, 1, 2, 3, 4, 5, 6, 7] | [-2, -1, 0, 1, 2, 3, 4, 5, 6] |
| Electronegativity (Pauling) | 3.16 | 2.55 |
| Electron affinity | 3.6127 eV | 2.0206 eV |
| Density | 3.214 kg/m³ | 4809 kg/m³ |
| Melting point | -101.5 °C | 220.5 °C |
| Boiling point | -34.04 °C | 684.85 °C |
| Discovery year | 1774 | 1817 |