Comparison of Thulium and Americium

Attribute	Americium ×	Thulium ×
Standard state	Solid	Solid
Electron configuration	[Rn]7s²5f⁷	[Xe]6s²4f¹³
Atomic mass (u)	243.06138	168.93422
Electronegativity (pauling scale)	1.3	1.25
Oxidation states	+3 +4 +5 +6	+3
Ionization energy (eV)	5.993	6.184
Atomic radius (van der waals) (pm)	244	227
Boiling point (K)	2284	2223
Melting point (K)	1449	1818
Density (g/cm³)	13.69	9.32
Atomic number	95	69
Group name	Actinide	Lanthanide
Discovered (year)	1944	1879
Symbol	Am	Tm