Uranium vs Neptunium

Side-by-side comparison of Uranium (U, element 92) and Neptunium (Np, element 93) by atomic structure and physical properties.

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PropertyU Uranium Np Neptunium
Atomic number9293
SymbolUNp
NameUraniumNeptunium
Categoryactinideactinide
Standard Atomic Weight238.02891 u237 u
Period77
GroupN/AN/A
Blockff
Phase at STPSolidSolid
Electron configuration[Rn]5f36d17s2[Rn]5f46d17s2
Oxidation states[-1, 1, 2, 3, 4, 5, 6][2, 3, 4, 5, 6, 7]
Electronegativity (Pauling)1.381.36
Electron affinity0.31497 eV0.48 eV
Density1.895e+4 kg/m³2.025e+4 kg/m³
Melting point1134.85 °C643.85 °C
Boiling point4130.85 °C3901.85 °C
Discovery year17891940

Key Differences

PropertyU UraniumNp Neptunium
Standard Atomic Weight238.02891 u ↑ higher237 u ↓ lower
Density1.895e+4 kg/m³ ↓ lower2.025e+4 kg/m³ ↑ higher
Melting point1134.85 °C ↑ higher643.85 °C ↓ lower
Boiling point4130.85 °C ↑ higher3901.85 °C ↓ lower
Electronegativity (Pauling)1.38 ↑ higher1.36 ↓ lower
Electron affinity0.31497 eV ↓ lower0.48 eV ↑ higher
Electron configuration[Rn]5f36d17s2 [Rn]5f46d17s2
Discovery year1789 1940