We use cookies and other tracking technologies to improve your browsing experience on our website, to show you personalized content and targeted ads, to analyze our website traffic, and to understand where our visitors are coming from. For more information, please review our cookie policy and privacy policy.
By choosing I Accept, you consent to our use of cookies and other tracking technologies.

Neptunium (Np)

Neptunium is a chemical element of the periodic table with chemical symbol Np and atomic number 93 with an atomic weight of 237 u and is classed as actinide. Neptunium is solid at room temperature.

Neptunium in the periodic table

SymbolNp
Atomic number93
Group-
Period7
Blockf
ClassificationActinide
AppearanceSilvery metallic
Color Silver
Number of protons93 p+
Number of neutrons144 n0
Number of electrons93 e-
From Wikipedia, the free encyclopediaNeptunium is a chemical element with symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. Its position in the periodic table just after uranium, named after the planet Uranus, led to it being named after Neptune, the next planet beyond Uranus.

Physical properties

Phase at STPSolid
Density20.45 g/cm3
Atomic weight237 u

Thermal properties

Melting point912 K
638.85 °C
1181.93 °F
Boiling point4447 K
4173.85 °C
7544.93 °F
Heat of vaporization336 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)1.36
Electron affinity45.85 kJ/mol
Oxidation states+2, +3, +4, +5, +6, +7
(an amphoteric oxide)
Ionization energies
  1. 604.5 kJ/mol
  2. 1128 kJ/mol
  3. 1997 kJ/mol
  4. 3242 kJ/mol

Electron configuration for neptunium

Electron configuration
Shorthand configuration
[Rn] 5f4 6d1 7s2
Electron configuration
Full configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f4 6s2 6p6 6d1 7s2
Electron configuration chart
1s2
2s22p6
3s23p63d10
4s24p64d104f14
5s25p65d105f4
6s26p66d1
7s2
Electrons per shell2, 8, 18, 32, 22, 9, 2
Valence electrons 2
Valency electrons 6
Bohr model
NeptuniumElectron shell for Neptunium, created by Injosoft ABNp
Figure: Shell diagram of Neptunium (Np) atom.
Orbital Diagram
1s
2s2p
3s3p3d
4s4p4d4f
5s5p5d5f
6s6p6d
7s

The history of Neptunium

DiscoveryEdwin McMillan, Philip H. Abelson (1940)

Identifiers

List of unique identifiers for Neptunium in various chemical registry databases
CAS Number7439-99-8
ChemSpider ID22375
EC number231-108-8
PubChem CID Number23933