Chlorine (Cl)
Chlorine (Cl) is element 17 of the periodic table, a halogen in period 3 and group 17. Its standard atomic weight is 35.45, so one mole of chlorine atoms has a mass of 35.45 g. At room temperature it is a gas; it melts at -101.5 °C and boils at -34.04 °C.
| Atomic number | 17 |
|---|---|
| Symbol | Cl |
| Standard atomic weight | 35.45 |
| Molar mass | 35.45 g/mol |
| Category | Halogen |
| Group | 17 |
| Period | 3 |
| Block | p-block |
| Electron configuration | [Ne] 3s2 3p5 |
| Oxidation states | +7, +5, +1, −1 |
| Electronegativity (Pauling) | 3.16 |
| Atomic radius (van der Waals) | 175 pm |
| First ionisation energy | 12.968 eV (1251.2 kJ/mol) |
| Electron affinity | 3.617 eV |
| State at room temperature | Gas |
| Melting point | 171.65 K (-101.5 °C) |
| Boiling point | 239.11 K (-34.04 °C) |
| Density | 3.214 g/L |
| Discovered | 1774 |
Group 17
Calculate with Chlorine
Atomic weight: IUPAC CIAAW standard atomic weight. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.