Comparison of Praseodymium and Neptunium

Attribute	Neptunium ×	Praseodymium ×
Standard state	Solid	Solid
Electron configuration	[Rn]7s²5f⁴6d¹	[Xe]6s²4f³
Atomic mass (u)	237.048172	140.90766
Electronegativity (pauling scale)	1.36	1.13
Oxidation states	+3 +4 +5 +6	+3
Ionization energy (eV)	6.266	5.464
Atomic radius (van der waals) (pm)	221	239
Boiling point (K)	4175	3793
Melting point (K)	917	1204
Density (g/cm³)	20.25	6.77
Atomic number	93	59
Group name	Actinide	Lanthanide
Discovered (year)	1940	1885
Symbol	Np	Pr