Comparison of Oxygen and Argon

Attribute	Argon ×	Oxygen ×
Atomic mass (u)	39.9	15.999
Standard state	Gas	Gas
Oxidation states	0	-2
Electron configuration	[Ne]3s²3p⁶	[He]2s²2p⁴
Atomic radius (van der waals) (pm)	188	152
Electronegativity (pauling scale)	-	3.44
Electron affinity (eV)	-	1.461
Ionization energy (eV)	15.76	13.618
Boiling point (K)	87.3	90.2
Melting point (K)	83.8	54.36
Density (g/cm³)	0.0017837	0.001429
Atomic number	18	8
Group name	Noble gas	Nonmetal
Symbol	Ar	O
Discovered (year)	1894	1774