Comparison of Chlorine and Bromine

Attribute	Chlorine ×	Bromine ×
Atomic mass (u)	35.45	79.9
Standard state	Gas	Liquid
Oxidation states	-1 +1 +5 +7	-1 +1 +5
Electron configuration	[Ne]3s²3p⁵	[Ar]4s²3d¹⁰4p⁵
Atomic radius (van der waals) (pm)	175	183
Electronegativity (pauling scale)	3.16	2.96
Electron affinity (eV)	3.617	3.365
Ionization energy (eV)	12.968	11.814
Boiling point (K)	239.11	331.95
Melting point (K)	171.65	265.95
Density (g/cm³)	0.003214	3.11
Atomic number	17	35
^1↑Group name	Halogen	Halogen
Discovered (year)	1774	1826
Symbol	Cl	Br