Element 17
Chlorine (Cl)
Chlorine (Cl) is element 17 of the periodic table, a halogen in period 3, group 17 (p-block) with an atomic mass of 35.45 and is a gas at standard conditions.
At a glance
- Atomic number
- 17
- Symbol
- Cl
- Atomic mass
- 35.45 u
- Category
- Halogens
- Period
- 3
- Group
- 17
- Block
- p-block
- Phase at STP
- gas
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p5
- Shorthand configuration
- [Ne] 3s2 3p5
- Electrons per shell
- 2, 8, 7
- Oxidation states
- -1, +1, +2, +3, +4, +5, +6, +7
Physical properties
- Melting point
- 171.6 K
- Boiling point
- 239.11 K
- Density
- 0.003214 g/cm3
- Phase
- gas
Atomic properties
- Electronegativity (Pauling)
- 3.16
- Atomic radius
- 79 pm
- Covalent radius
- 102 pm
- Van der Waals radius
- 175 pm
- First ionization energy
- 1251 kJ/mol
- Electron affinity
- 349 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Cl-35 | 34.96885 | 75.76% | Stable |
Common uses
- Water treatment
- PVC plastic
- Disinfectants
- Bleach
Discovery
- Year
- 1774
- Discovered by
- Carl Wilhelm Scheele
- Country
- Sweden