Chlorine

Chaitra 26/06/2026 19:58:08 Updated 26/06/2026 19:58:08

Property	Value
Atomic Number	17
Element	Chlorine
Symbol	Cl
Atomic Mass	35.45 u
Number of Neutrons	18 (most common isotope, Chlorine-35)
Number of Protons	17
Number of Electrons	17
Period	3
Group	17
Phase	Gas
Radioactive	No
Natural	Yes
Metal	No
Nonmetal	Yes
Metalloid	No
Type	Halogen
Atomic Radius	79 pm
Electronegativity	3.16 (Pauling scale)
First Ionization Energy	12.968 eV
Density	0.003214 g/cm³
Melting Point	−101.5 °C
Boiling Point	−34.04 °C
Number of Isotopes	2 stable (Chlorine-35, Chlorine-37)
Discoverer	Carl Wilhelm Scheele
Year	1774
Specific Heat	0.479 J/g·K
Number of Shells	3
Number of Valence Electrons	7