Technical data for Neptunium

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
Heat of Fusion10 kJ/mol
Heat of Vaporization335 kJ/mol
Heat of CombustionN/A
Specific HeatN/A
Thermal Conductivity6 W/(m K)
Thermal ExpansionN/A

Bulk physical properties
Density20.45 g/cm3
Density (Liquid)N/A
Molar Volume0.0000115892
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

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

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

Notes on the properties of Neptunium:
Atomic Weight: Atomic mass number given for longest lived isotope.