Neptunium , including Technical Data, Safety Data and its high purity properties, research, applications and other useful facts are discussed below. Scientific facts such as the atomic structure,ionization energy, abundance on Earth, conductivity and thermal properties are included. 

Neptunium is a Block F, Group 3, Period 7 element. The number of electrons in each of Neptunium‘s shells is 2, 8, 18, 32, 22, 9, 2 and its electronic configuration is [Rn] 5f4 6d1 7s2. In its elemental form neptunium ‘s CAS number is 7439-99-8. The neptunium atom has a radius of 130.pm and it‘s Van der Waals radius is 200.pm. 

Neptunium was discovered by Edwin M. McMillan and P. H. Abelson in 1940.

Neptunium was named for the planet Neptune. 

Neptunium Abundance. The following table shows the abundance of neptunium and each of its naturally occurring isotopes on Earth along with the atomic mass for each isotope. Isotope Atomic Mass % Abundance on Earth Np-237 237.048167 - Neptunium Safety Data. The safety data for neptunium metal, nanoparticles and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the left margin. Neptunium compounds have no biological role.  Ionization Energy. The ionization energy for neptunium (the least required energy to release a single electron from the atom in it‘s ground state in the gas phase) is stated in the following table: 1st Ionization Energy 604.55 kJ mol-1 2nd Ionization Energy - kJ mol-1 3rd Ionization Energy - kJ mol-1 Conductivity. As to neptunium ‘s electrical and thermal conductivity, the electrical conductivity measured in terms of electrical resistivity @ 20 ?C is 122 ?Ocm and its electronegativities (or its ability to draw electrons relative to other elements) is 1.3. The thermal conductivity of neptunium is 6.3 W m-1 K-1.  Thermal Properties of Neptunium . The melting point and boiling point for neptunium are stated below. The following chart sets forth the heat of fusion, heat of vaporization and heat of atomization. Heat of Fusion 9.46kJ mol-1 Heat of Vaporization 336.6 kJ mol-1 Heat of Atomization 457 kJ mol-1

Formula	Atomic Number	Molecular Weight	Electronegativity (Pauling)	Density	Melting Point	Boiling Point	Vanderwaals radius	Ionic radius	Energy of first ionization
Np	93	237 g.mol -1	1.36	20.2 g/L	637? °C	4000 °C	.200 nm	130 pm	604.55 kJ.mol-1