Cl
Chlorine
Atomic number: 17Mass: 35.45 uCategory: Halogen
About Chlorine
Chlorine is a yellow-green gas that is extremely reactive. It is the second lightest halogen. Chlorine is widely used for purifying water and as a disinfectant. Sodium chloride (table salt) is its most common compound.
Properties
Period
3
Group
17
Block
P
Category
Halogen
Electronegativity
3.16 (Pauling)
Ionization Energy
1251.2 kJ/mol
Melting Point
172 K (-102°C)
Boiling Point
239 K (-34°C)
Density
3.214 g/L
Oxidation States
-1, +1, +3, +5, +7
Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁵
[Ne] 3s² 3p⁵
Shell 1:2e⁻
Shell 2:8e⁻
Shell 3:7e⁻
Real-World Uses
Water purification
PVC plastic
Bleach
Disinfectants
Pharmaceuticals
Fun Fact
Chlorine was used as a chemical weapon in World War I, but today it saves millions of lives each year by purifying drinking water.