Comparison of Actinium and Plutonium

Attribute	Plutonium ×	Actinium ×
Standard state	Solid	Solid
Electron configuration	[Rn]7s²5f⁶	[Rn]7s²6d¹
Atomic mass (u)	244.0642	227.02775
Electronegativity (pauling scale)	1.28	1.1
Oxidation states	+3 +4 +5 +6	+3
Ionization energy (eV)	6.06	5.17
Atomic radius (van der waals) (pm)	243	260
Boiling point (K)	3501	3471
Melting point (K)	913	1324
Density (g/cm³)	19.84	10.07
Atomic number	94	89
Group name	Actinide	Actinide
Discovered (year)	1940	1899
Symbol	Pu	Ac