Comparison of Praseodymium and Actinium

Attribute	Actinium ×	Praseodymium ×
Standard state	Solid	Solid
Electron configuration	[Rn]7s²6d¹	[Xe]6s²4f³
Atomic mass (u)	227.02775	140.90766
Electronegativity (pauling scale)	1.1	1.13
Oxidation states	+3	+3
Ionization energy (eV)	5.17	5.464
Atomic radius (van der waals) (pm)	260	239
Boiling point (K)	3471	3793
Melting point (K)	1324	1204
Density (g/cm³)	10.07	6.77
Atomic number	89	59
Group name	Actinide	Lanthanide
Discovered (year)	1899	1885
Symbol	Ac	Pr