Comparison of Samarium and Thulium

Attribute	Thulium ×	Samarium ×
Standard state	Solid	Solid
Electron configuration	[Xe]6s²4f¹³	[Xe]6s²4f⁶
Atomic mass (u)	168.93422	150.4
Electronegativity (pauling scale)	1.25	1.17
Oxidation states	+3	+2 +3
Ionization energy (eV)	6.184	5.644
Atomic radius (van der waals) (pm)	227	229
Boiling point (K)	2223	2067
Melting point (K)	1818	1347
Density (g/cm³)	9.32	7.52
Atomic number	69	62
Group name	Lanthanide	Lanthanide
Discovered (year)	1879	1879
Symbol	Tm	Sm