Thulium

Lanthanide · 168.93422 u · group 3, period 6

Thulium · Tm

Atomic number69

SymbolTm

CategoryLanthanide

Standard stateSolid

Group · Period · Block3 · 6 · f

Electron configuration[Xe]6s2 4f13

Atomic mass168.93422 u

Atomic radius227 pm

Protons / Neutrons / Electrons69 / 100 / 69

Shells (e⁻ per shell)2, 8, 18, 31, 8, 2

Electronegativity (Pauling)1.25

Ionization energy6.184 eV

Electron affinity—

Oxidation states+3

Melting point1.82e+3 K · 1.54e+3 °C

Boiling point2.22e+3 K · 1.95e+3 °C

Density9.32 g/cm³

Year discovered1879

CPK color

#00D452

State at room temp (25 °C)

solid

Position