Definition of the Neptunium Element
A radioactive metallic element that is chemically similar to uranium and is obtained in nuclear reactors as a by-product in the production of plutonium. Chemically, Neptunium is extremely reactive and is attacked by Oxygen, steam and acids, but not by alkalis. The Atomic Number of this element is 93 and the Element Symbol is Np.

Origin / Meaning of the name Neptunium
Neptunium  was named for the planet Neptune because it is the next outer-most planet beyond the planet Uranus in the solar system and this element is the next one beyond uranium in the periodic table.

Facts about the Discovery and History of the Neptunium Element
Neptunium was discovered by Edwin McMillan and Philip Abelson in the USA in 1940

History of the Periodic Table
Check out the brief History of the Periodic Table which details dates and the names of famous scientists and chemists who contributed to the development of the Periodic Table.

Occurrence of the Neptunium Element
Man-made

Abundances of the element in different environments
% in Universe N/A
% in Sun None
% in Meteorites None
% in Earth's Crust None
% in Oceans None
% in Humans None

Associated Uses of Neptunium
Neutron detection equipment

The Properties of the Neptunium Element
Name of Element : Neptunium
Symbol: Np
Atomic Number: 93
Atomic Mass: (237.0) amu
Melting Point: 640.0 °C - 913.15 °K
Boiling Point: 3902.0 °C - 4175.15 °K
Number of Protons/Electrons: 93
Number of Neutrons: 144
Crystal Structure: Orthorhombic
Density @ 293 K: 20.45 g/cm3
Color: Silvery

Neptunium as on the Periodic Table
Check out Neptunium on the Periodic Table which arranges each chemical element according to its atomic number, as based on the Periodic Law, so that chemical elements with similar properties are in the same column. Our Periodic Table is simple to use - just click on the symbol for Neptunium as on the Periodic Table for additional information and for an instant comparison of the Atomic Weight, Melting Point, Boiling Point and Mass - G/cc with any other element. An invaluable source of facts and information as a Chemistry reference guide.

What is Neptunium - IUPAC and the Modern Standardised Periodic Table
The Standardised Periodic Table in use today was agreed by the International Union of Pure Applied Chemistry, IUPAC, in 1985 and now recognises more periods and elements than Dimitri  Mendeleev knew in his day in his day but still all fitting into his concept of  the "Periodic Table" in which Neptunium is just one element that can be found.

Learn about what is Neptunium with these fast facts...
These articles contain facts and information relating to Neptunium and each of the other elements including the Periodic Symbol,  group, classification, properties and atomic number which is often referred to as the Periodic Table Number. Test your knowledge of chemistry and the Periodic Table by completing the Element Symbols and Atomic Numbers on our Blank Periodic Table. Chemistry students will also find a helpful section on Chemical Formulas.