Neptunium

Neptunium (Np)

Radioactive metallic transuranic element, belongs to the actinoids. Np-237, the most stable isotope, has a half-life of 2.2*10^6 years and is a by product of nuclear reactors. The other known isotopes have mass numbers 229 through 236, and 238 through 241. Np-236 has a half-life of 5*10^3 years. First produced by Edwin M. McMillan and P.H. Abelson in 1940.
Atomic Number93
Atomic Weight237
Mass Number225
Group
Period7
Blockf
Protons93 p+
Neutrons132 n0
Electrons93 e-
Neptunium2.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
175 pm
Atomic Volume
Covalent Radius
171 pm
Metallic Radius
Ionic Radius
110.00000000000001 pm
Crystal Radius
124 pm
Van der Waals radius
239 pm
Density
20.2 g/cm³
Boiling Point
4,175 K
Melting Point
913 K
Electrons per shell2, 8, 18, 32, 22, 9, 2
Electronegativity
1.3
Electrophilicity
Proton Affinity
Electron Affinity
Ionization Potential
Heat of Vaporization
336 kJ/mol
Heat of Fusion
9.6 kJ/mol
Heat of Formation
464.8 kJ/mol
Molar Heat Capacity
Specific Heat Capacity
Thermal Conductivity
Gas Basicity
Dipole Polarizability
151 a₀
C6 Dispersion Coefficient
Oxidation States3, 4, 5, 6, 7
Color
Silver
Crystal StructureSimple Orthorhombic (ORC)
Lattice Constant
4.72 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Rn] 5f4 6d1 7s2
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryActinides, Actinides
CAS Group
IUPAC Group
Glawe Number37
Mendeleev Number22
Pettifor Number44
Geochemical Class
Goldschmidt Classsynthetic
Radioactivity
RadioactiveYes ☢️
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
Abundance in Oceans
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universena

Isotopes of Neptunium

Stable Isotopes
Unstable Isotopes
225Np 226Np 227Np 228Np 229Np 230Np 231Np 232Np 233Np 234Np 235Np 236Np 237Np 238Np 239Np 240Np 241Np 242Np 243Np 244Np

History

Neptunium was the first synthetic transuranium element of the actinide series to be discovered. Neptunium was first produced by Edwin McMillan and Philip H. Abelson in 1940 at Berkeley Radiation Laboratory of the University of California. The team produced the neptunium isotope 239Np by bombarding uranium with slow moving neutrons. Named after the planet Neptune

DiscoverersE.M. McMillan, P.H. Abelson
Discovery LocationUnited States
Discovery Year1940
Name OriginNamed for the planet Neptune.
Neptunium is harmful due to its radioactivity
Neptunium is obtained as a by-product from nuclear reactors

Uses

Neptunium is used mainly for research purposes. When bombarded with neutrons 237Np is used to produce 238Pu which is used for spacecraft generators and terrestrial navigation beacons. 237Np is used in devices for detecting high-energy neutrons. It has no significant commercial applications.

Sources

Produced by bombarding uranium with slow neutrons.