| Property | Unit | Value |
| Name | - | Neptunium |
| Abbrevation | - | Np |
| Atomic Number | - | 93 |
| Group | - | RE |
| Heat of Fusion | Kcal/g-mole | N/A |
| Heat of Vaporization | Kcal/g-mole | N/A |
| Molecular Weight | g/g-mole | 237.04820 |
| Melting Point | �C | 640 |
| Boiling Point | �C | 3901.85 |
| Refractive Index | - | N/A |
| Critical Temperature | �C | N/A |
| Critical Pressure | atm | N/A |
| Critical Volume | cm�/g-mol | N/A |
| Atomic Volume | cm�/g-mol | 11.59 |
| Atomic Radii (Bragg-Slater) | pm | N/A |
| Atomic Radii (Covalent) | pm | N/A |
| Atomic Radii (Van der Walls) | pm | N/A |
| Density | g/cm� | 20.25000 |
| Oxidation State | - | 5,3,4,6 |
| Electron Configuration | - | [Rn]5f4 6d 7s2 |
| Electron Affinity (Theory) | KJ/g-mol | N/A |
| Electron Affinity (Exp) | KJ/g-mol | N/A |
| Electronegativity (Pauling) | - | 1.30 |
| Electronegativity (Sanderson) | - | N/A |
| Electronegativity (Allred_Rochow) | - | 1.22 |
| Surface Tension @BP | dyn/cm | N/A |
| NMR Frequencies of Nuclei | MHz | 11.25 |
| Discovery Date | - | 1940 |
| Electric Resistivity | mohm-cm | 122 |
| Linear Thermal Expansion Coefficient | 1E-6 cm/cm/�C | 27.5 |
| Neutron Capture Cross Section | barns | 170 |
| Thermal Conductivity | W/m/K | 6.3 |
| Magnetic Susceptibility | 1e-9 m�/kg | NA |
| Abundance, (Sun) | log(atoms/1E12 atoms H) | N/A |
| Abundance, (Meteorite) | log(atoms/atoms) | N/A |
| Abundance, (Earth) | log(pbbw) | N/A |
| Abundance, (Crust) | log(pbbw) | N/A |
| Abundance, (Ocean) | log(1E-12 mol/kg) | N/A |
| Abundance, (Body) | log(ppmw) | N/A |
| Electrical Conductivity | %IACS | N/A |
| Electrical Resistance | - | 118 |
| Photoelectric Work Function | eV | N/A |
| Hall's Coefficient | 1E-12* volt-cm/amp-Oe | N/A |
| Electrochemical Equivalent | mg/coulomb | N/A |
| Young's Modulus of Elasticity | 1E-6 kg/cm� | 1.02 |
| Shear Modulus | 1E-6 kg/cm� | 0.406 |
| Bulk Modulus | 1E-6 kg/cm� | 0.694 |
| Poisson's Ratio | - | 0.255 |
| Hardness | - | N/A |
| Hardness Unit | - |
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