Comparison of Krypton and Francium

Attribute	Francium ×	Krypton ×
Standard state	Solid	Gas
Electron affinity (eV)	0.47	-
Electron configuration	[Rn]7s¹	[Ar]4s²3d¹⁰4p⁶
Atomic mass (u)	223.01973	83.8
Electronegativity (pauling scale)	0.7	3
Oxidation states	+1	0
Ionization energy (eV)	3.9	14
Atomic radius (van der waals) (pm)	348	202
Boiling point (K)	-	119.93
Melting point (K)	300	115.79
Density (g/cm³)	-	0.003733
Atomic number	87	36
Group name	Alkali metal	Noble gas
Symbol	Fr	Kr
Discovered (year)	1939	1898