69Tm

Thulium

Lanthanide

Thulium (Tm) is element 69, a lanthanide, in period 6 of the periodic table. Its standard atomic weight is 168.934, it melts at 1545 °C and boils at 1950 °C. Discovered by Per Teodor Cleve, 1879.

Atomic Number69

SymbolTm

NameThulium

Atomic Weight168.934 u

CategoryLanthanide

Period6

Melting Point1545 °C

Boiling Point1950 °C

Density9.321 g/cm³

Electron Config[Xe] 4f13 6s2

Discovered ByPer Teodor Cleve, 1879

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