Chlorine · Cl Chlorine
is used in chloride chemical industry and water treatment; chloride ions are important electrolytes.
- atomic number / Atomic number
- 17
- atomic weight / Atomic mass
- 35.45 u
- Family/Group
- 17
- Period · Block / Period · Block
- 3 · p
- Category / Category
- Halogen The · Halogen
- State / State
- gaseous state
- Electron configuration
- [Ne]3s2 3p5
- Oxidation states / Oxidation states
- +7, +5, +1, -1
- Electronegativity / Electronegativity
- 3.16（Pauling）
- Density / Density
- 0.003214 g/cm³
- Melting point / Melting point
- 171.65 K
- Boiling point / Boiling point
- 239.11 K
- Atomic radius / Atomic radius
- 175 pm（van der Waals）
- First ionization energy
- 12.968 eV
- Discovery year / Discovery
- 1774
attribute description and data source
properties taken from PubChem periodic table snapshot (2026-10-04). Atomic weights may be reference values or representative isotope masses and cannot be considered exact constants for all samples; density, phase transition points, and phase states depend on temperature, pressure, and allotropes. The solidification of helium requires pressure. Some properties of radioactive and superheavy elements are predicted values, and missing items are marked as not included. Please check the original source and experimental conditions for precise calculations.