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17
Cl
35.45
Chlorine
Halogens · Group 17 · Period 3
Atomic properties
| Atomic number | 17 |
|---|---|
| Symbol | Cl |
| Standard atomic weight | 35.45 |
| Classification | Halogens |
| Group | 17 |
| Period | 3 |
| Block | p-block |
| Electron configuration | [Ne] 3s2 3p5 |
| Electronegativity (Pauling) | 3.16 |
| Common oxidation states | +7, +5, +1, -1 |
Physical properties
| Phase at 20 °C | Gas |
|---|---|
| Density | 0.003214 g/cm³ |
| Melting point | -101.5 °C |
| Boiling point | -34.04 °C |
| Discovered | 1774 |
| CAS number | — |