Comparison of Argon and Francium

Attribute	Francium ×	Argon ×
Electron affinity (eV)	0.47	-
Electronegativity (pauling scale)	0.7	-
Atomic mass (u)	223.01973	39.9
Standard state	Solid	Gas
Oxidation states	+1	0
Electron configuration	[Rn]7s¹	[Ne]3s²3p⁶
Ionization energy (eV)	3.9	15.76
Atomic radius (van der waals) (pm)	348	188
Boiling point (K)	-	87.3
Melting point (K)	300	83.8
Density (g/cm³)	-	0.0017837
Atomic number	87	18
Group name	Alkali metal	Noble gas
Discovered (year)	1939	1894
Symbol	Fr	Ar