Neodymium vs Promethium

Side-by-side comparison of Neodymium (Nd, element 60) and Promethium (Pm, element 61) by atomic structure and physical properties.

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PropertyNd Neodymium Pm Promethium
Atomic number6061
SymbolNdPm
NameNeodymiumPromethium
Categorylanthanidelanthanide
Standard Atomic Weight144.242 u145 u
Period66
GroupN/AN/A
Blockff
Phase at STPSolidSolid
Electron configuration[Xe]4f46s2[Xe]4f56s2
Oxidation states[0, 2, 3, 4][2, 3]
Electronegativity (Pauling)1.14N/A
Electron affinity0.09749 eV0.129 eV
Density7010 kg/m³7260 kg/m³
Melting point1020.85 °C1041.85 °C
Boiling point3073.85 °C2999.85 °C
Discovery year18411945

Key Differences

PropertyNd NeodymiumPm Promethium
Standard Atomic Weight144.242 u ↓ lower145 u ↑ higher
Density7010 kg/m³ ↓ lower7260 kg/m³ ↑ higher
Melting point1020.85 °C ↓ lower1041.85 °C ↑ higher
Boiling point3073.85 °C ↑ higher2999.85 °C ↓ lower
Electron affinity0.09749 eV ↓ lower0.129 eV ↑ higher
Electron configuration[Xe]4f46s2 [Xe]4f56s2
Discovery year1841 1945