17 Cl 35.45

Chlorine

Reactive Nonmetal

Chlorine (Cl) is a chemical element with atomic number 17, classified as a reactive nonmetal. At room temperature it is a gas. It was discovered in 1774 by Carl Wilhelm Scheele.

Properties

Atomic number
17
Atomic mass
35.45 u
Category
Reactive Nonmetal
Group
17
Period
3
Block
p-block
Electron configuration
[Ne] 3s² 3p⁵
Phase at STP
Gas
Density
3.214 g/L
Melting point
171.65 K (-101.5 °C)
Boiling point
239.11 K (-34.0 °C)
Electronegativity
3.16
Atomic radius
79 pm
Ionization energy
12.968 eV
Discovery
1774 · Carl Wilhelm Scheele

Common uses

Water purification, bleach, PVC plastic, table salt

Did you know?

Poisonous gas that saves millions of lives by disinfecting drinking water.