Comparison of Promethium and Curium

Attribute	Curium ×	Promethium ×
Electronegativity (pauling scale)	1.3	-
Atomic mass (u)	247.07035	144.91276
Standard state	Solid	Solid
Oxidation states	+3	+3
Electron configuration	[Rn]7s²5f⁷6d¹	[Xe]6s²4f⁵
Ionization energy (eV)	6.02	5.55
Atomic radius (van der waals) (pm)	245	236
Boiling point (K)	3400	3273
Melting point (K)	1618	1315
Density (g/cm³)	13.51	7.26
Atomic number	96	61
Group name	Actinide	Lanthanide
Discovered (year)	1944	1945
Symbol	Cm	Pm