Comparison of Protactinium and Einsteinium

Attribute	Einsteinium ×	Protactinium ×
Atomic mass (u)	252.083	231.03588
Standard state	Solid	Solid
Oxidation states	+3	+4 +5
Electron configuration	[Rn]7s²5f¹¹	[Rn]7s²5f²6d¹
Atomic radius (van der waals) (pm)	245	243
Electronegativity (pauling scale)	1.3	1.5
Melting point (K)	1133	1845
Ionization energy (eV)	6.42	5.89
Density (g/cm³)	-	15.37
Atomic number	99	91
Group name	Actinide	Actinide
Symbol	Es	Pa
Discovered (year)	1952	1913