Comparison of Protactinium and Berkelium

Attribute	Berkelium ×	Protactinium ×
Atomic mass (u)	247.07031	231.03588
Standard state	Solid	Solid
Oxidation states	+3 +4	+4 +5
Electron configuration	[Rn]7s²5f⁹	[Rn]7s²5f²6d¹
Atomic radius (van der waals) (pm)	244	243
Electronegativity (pauling scale)	1.3	1.5
Melting point (K)	1323	1845
Ionization energy (eV)	6.23	5.89
Density (g/cm³)	14	15.37
Atomic number	97	91
Group name	Actinide	Actinide
Discovered (year)	1949	1913
Symbol	Bk	Pa