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Technical data for Neptunium

Click any property name to see plots of that property for all the elements.

Overview
NameNeptunium
SymbolNp
Atomic Number93
Atomic Weight237[note]
Density20.45 g/cm3
Melting Point644 °C
Boiling Point4×103 °C

Thermal properties
PhaseSolid
Melting Point644 °C
Boiling Point4×103 °C
Absolute Melting Point917 K
Absolute Boiling Point4273 K
Critical PressureN/A
Critical TemperatureN/A
Heat of Fusion10 kJ/mol
Heat of Vaporization335 kJ/mol
Heat of CombustionN/A
Specific HeatN/A
Adiabatic IndexN/A
Neel PointN/A
Thermal Conductivity6 W/(m K)
Thermal ExpansionN/A

Bulk physical properties
Density20.45 g/cm3
Density (Liquid)N/A
Molar Volume0.0000115892
Brinell HardnessN/A
Mohs HardnessN/A
Vickers HardnessN/A
Bulk ModulusN/A
Shear ModulusN/A
Young ModulusN/A
Poisson RatioN/A
Refractive IndexN/A
Speed of SoundN/A
Thermal Conductivity6 W/(m K)
Thermal ExpansionN/A

Reactivity
Valence6
Electronegativity1.36
ElectronAffinityN/A
Ionization Energies
604.5 kJ/mol

Health and Safety
Autoignition PointN/A
FlashpointN/A
Heat of CombustionN/A
DOT Hazard ClassN/A
DOT NumbersN/A
EU NumberN/A
NFPA Fire RatingN/A
NFPA HazardsN/A
NFPA Health RatingN/A
NFPA Reactivity RatingN/A
RTECS NumberN/A
NFPA LabelN/A

Classifications
Alternate NamesNone
Names of AllotropesNone
Blockf
GroupN/A
Period7
Electron Configuration[Rn]5f46d17s2
ColorSilver
Discovery
1940 in United States
Gas phaseN/A
CAS NumberCAS7439-99-8
CID NumberN/A
Gmelin NumberN/A
NSC NumberN/A
RTECS NumberN/A

Electrical properties
Electrical TypeConductor
Electrical Conductivity8.3×105 S/m
Resistivity1.2×10-6 m Ω
Superconducting PointN/A

Magnetic properties
Magnetic TypeN/A
Curie PointN/A
Mass Magnetic SusceptibilityN/A
Molar Magnetic SusceptibilityN/A
Volume Magnetic SusceptibilityN/A

Abundances
% in UniverseN/A
% in SunNone
% in MeteoritesNone
% in Earth's CrustNone
% in OceansNone
% in HumansNone

Atomic dimensions and structure
Atomic RadiusN/A
Covalent RadiusN/A
Van der Waals RadiusN/A
Crystal StructureSimple Orthorhombic
Lattice Angles
π/2, π/2, π/2
Lattice Constants
666.3, 472.3, 488.7 pm
Space Group NamePnma
Space Group Number62

Nuclear Properties
Half-Life2.1455×106 y
Lifetime3.0952×106 y
Decay ModeAlphaEmission
Quantum Numbers6L11/2
Neutron Cross Section180
Neutron Mass AbsorptionN/A
Known Isotopes
225Np, 226Np, 227Np, 228Np, 229Np, 230Np, 231Np, 232Np, 233Np, 234Np, 235Np, 236Np, 237Np, 238Np, 239Np, 240Np, 241Np, 242Np, 243Np, 244Np
Stable Isotopes
Isotopic Abundances


Notes on the properties of Neptunium:

Atomic Weight: Atomic mass number given for longest lived isotope.

Up to date, curated data provided by
Mathematica's ElementData function from Wolfram Research, Inc.

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