Terbium vs Erbium

PropertyTb TerbiumEr Erbium
Atomic number6568
SymbolTbEr
NameTerbiumErbium
Categorylanthanidelanthanide
Standard Atomic Weight158.92535 u167.259 u
Period66
GroupN/AN/A
Blockss
Phase at STPsolidsolid
Electron configuration[Xe]6s24f9[Xe]6s24f12
Oxidation states[0, 1, 2, 3, 4][0, 1, 2, 3]
Electronegativity (Pauling)N/A1.24
Electron affinity1.124 eV0.312 eV
Density8230 kg/m³9070 kg/m³
Melting point1355.85 °C1528.85 °C
Boiling point3229.85 °C2867.85 °C
Discovery year18431843