Comparison of Selenium and Cadmium

Attribute	Cadmium ×	Selenium ×
Atomic mass (u)	112.41	78.97
Standard state	Solid	Solid
Oxidation states	+2	-2 +4 +6
Electron configuration	[Kr]5s²4d¹⁰	[Ar]4s²3d¹⁰4p⁴
Atomic radius (van der waals) (pm)	158	190
Electronegativity (pauling scale)	1.69	2.55
Electron affinity (eV)	-	2.021
Ionization energy (eV)	8.994	9.752
Boiling point (K)	1040	958
Melting point (K)	594.22	493.65
Density (g/cm³)	8.69	4.809
Atomic number	48	34
Group name	Transition metal	Nonmetal
Symbol	Cd	Se
Discovered (year)	1817	1817