Comparison of Sodium and Selenium

Attribute	Selenium ×	Sodium ×
Atomic mass (u)	78.97	22.9897693
Standard state	Solid	Solid
Oxidation states	-2 +4 +6	+1
Electron configuration	[Ar]4s²3d¹⁰4p⁴	[Ne]3s¹
Atomic radius (van der waals) (pm)	190	227
Electronegativity (pauling scale)	2.55	0.93
Electron affinity (eV)	2.021	0.548
Ionization energy (eV)	9.752	5.139
Boiling point (K)	958	1156
Melting point (K)	493.65	370.95
Density (g/cm³)	4.809	0.97
Atomic number	34	11
Group name	Nonmetal	Alkali metal
Discovered (year)	1817	1807
Symbol	Se	Na