Chlorine (Cl) — Element 17: Properties & Data | Aladdin Scientific
Chlorine(Cl) — Element 17
Chlorine (Cl) is a halogen with atomic number 17 and atomic mass 35.45. It has melting point 171.65 K (-101 °C), boiling point 239.11 K (-34 °C), density 0.003214 g/cm³. It sits in group 17 and period 3 of the periodic table and was discovered in 1774.
Key facts
| Atomic mass | 35.4500 u |
|---|---|
| Electron configuration | [Ne]3s2 3p5 |
| Oxidation states | +7, +5, +1, -1 |
| Electronegativity (Pauling) | 3.16 |
| Atomic radius (van der Waals) | 175 pm |
| Ionization energy | 12.968 eV |
| Electron affinity | 3.617 eV |
| Melting point | 171.65 K |
| Boiling point | 239.11 K |
| Density | 0.003214 g/cm³ |
| Standard state | Gas |
| Year discovered | 1774 |
Frequently asked questions
What is the electron configuration of chlorine?
The ground-state electron configuration of chlorine is [Ne]3s2 3p5.
What group and period is chlorine in?
Chlorine (Cl) is in group 17 and period 3 of the periodic table, classified as a halogen.
What is the melting point of chlorine?
Chlorine melts at 171.65 K (-101 °C).
What is the standard state of chlorine?
Chlorine is a gas at standard temperature and pressure.
Related elements
About this data: property values compiled from IUPAC Standard Atomic Weights (2021), the NIST Atomic Spectra Database, and PubChem. Curated by the Aladdin Scientific technical team. Last reviewed: .