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Neptunium

Metal radioactivesolid
Symbol: Np
Atomic number: 93
Atomic mass: (237.0482)
Group: Actinide
CAS-number: 7439-99-8

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Physical data
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Physical data

Electronic dataThermal dataSteric data
Shells: 2, 8, 18, 32, 22, 9, 2
Orbitals: [Rn] 5f4 6d1 7s2
Electronegativity: --, 1.2
1. Ionization potential: 6.2657 eV
2. Ionization potential: -- eV
3. Ionization potential: -- eV
Oxidation states: 6, 5, 4, 3
Electrical conductivity: 0.00822 10^6
Melting point: 640 °C
Boiling point: 3902 °C
Specific heat: 0.12 J/gK
Heat of fusion: 5.190 kJ/mol
Heat of vaporization: -- kJ/mol
Thermal conductivity: 0.063 W/cmK
Atomic radius: -- Å
Ionic radius: -- Å
Covalent radius: -- Å
Atomic volume: 11.62 cm³/mol
Density (293 K): 20.45 g/cm³
Crystal structure: orthorhombic
orthorhombic

Isotopes

NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
235Np 0 235 5/2 1.085y EC, α View
236Np 0 236 6 1.55E05y EC, β- View
236Npm 0 236.047 1 22.5h EC, β- View
237Np 0 237.048 5/2 2.14E06y α View
238Np 0 238 2 2.117d β- View
239Np 0 239 5/2 2.355d β- View
240Np 0 240 5 1.032h β- View
240Npm 0 240 1 7.22m β-, IT View

Other info

Name origin:Named for the planet Neptune.
Description:Rare, silvery radioactive metal.
Discovered by:E.M. McMillan, P.H. Abelson
Year:1940
Place:United States
Sources:Produced by bombarding uranium with slow neutrons.
Use(s):It has no significant commercial applications.