Tools · Chemistry

Neptunium (Np)

Neptunium (Np) is element 93 of the periodic table, an actinide in period 7, in the f-block. It has no stable isotope and no standard atomic weight; 237 is the mass number of its longest-lived isotope. At room temperature it is a solid; it melts at 643.85 °C and boils at 3901.85 °C.

93 Np Neptunium [237]

Period 7, f-block · Actinide

← U Uranium Pu Plutonium →

Atomic number	93
Symbol	Np
Standard atomic weight	[237] (mass number of the longest-lived isotope)
Molar mass	[237] g/mol
Category	Actinide
Group	f-block (actinide series)
Period	7
Block	f-block
Electron configuration	[Rn] 7s² 5f⁴ 6d¹
Oxidation states	+6, +5, +4, +3
Electronegativity (Pauling)	1.36
Atomic radius (van der Waals)	221 pm
First ionisation energy	6.266 eV (604.6 kJ/mol)
Electron affinity	—
State at room temperature	Solid
Melting point	917 K (643.85 °C)
Boiling point	4175 K (3901.85 °C)
Density	20.25 g/cm³
Discovered	1940

Actinides

Ac · Actinium Th · Thorium Pa · Protactinium U · Uranium Pu · Plutonium Am · Americium Cm · Curium Bk · Berkelium Cf · Californium Es · Einsteinium Fm · Fermium Md · Mendelevium No · Nobelium

Calculate with Neptunium

Molar mass of Np Balance an equation Grams, moles and particles Whole periodic table

Atomic weight: IUPAC CIAAW — no standard atomic weight; mass number in brackets. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.