Holmium vs Erbium

Side-by-side comparison of Holmium (Ho, element 67) and Erbium (Er, element 68) by atomic structure and physical properties.

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PropertyHo Holmium Er Erbium
Atomic number6768
SymbolHoEr
NameHolmiumErbium
Categorylanthanidelanthanide
Standard Atomic Weight164.93033 u167.259 u
Period66
GroupN/AN/A
Blockff
Phase at STPSolidSolid
Electron configuration[Xe]4f116s2[Xe]4f126s2
Oxidation states[0, 1, 2, 3][0, 1, 2, 3]
Electronegativity (Pauling)1.231.24
Electron affinity0.338 eV0.312 eV
Density8800 kg/m³9070 kg/m³
Melting point1473.85 °C1528.85 °C
Boiling point2699.85 °C2867.85 °C
Discovery year18781843

Key Differences

PropertyHo HolmiumEr Erbium
Standard Atomic Weight164.93033 u ↓ lower167.259 u ↑ higher
Density8800 kg/m³ ↓ lower9070 kg/m³ ↑ higher
Melting point1473.85 °C ↓ lower1528.85 °C ↑ higher
Boiling point2699.85 °C ↓ lower2867.85 °C ↑ higher
Electronegativity (Pauling)1.23 ↓ lower1.24 ↑ higher
Electron affinity0.338 eV ↑ higher0.312 eV ↓ lower
Electron configuration[Xe]4f116s2 [Xe]4f126s2
Discovery year1878 1843