Comparison of Potassium and Selenium

Attribute	Selenium ×	Potassium ×
Atomic mass (u)	78.97	39.0983
Standard state	Solid	Solid
Oxidation states	-2 +4 +6	+1
Electron configuration	[Ar]4s²3d¹⁰4p⁴	[Ar]4s¹
Atomic radius (van der waals) (pm)	190	275
Electronegativity (pauling scale)	2.55	0.82
Electron affinity (eV)	2.021	0.501
Ionization energy (eV)	9.752	4.341
Boiling point (K)	958	1032
Melting point (K)	493.65	336.53
Density (g/cm³)	4.809	0.89
Atomic number	34	19
Group name	Nonmetal	Alkali metal
Discovered (year)	1817	1807
Symbol	Se	K