Chemical element · Atomic number 93
Neptunium
Neptunium in the periodic table: atomic number 93, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Actinide
solid
[237.048172] u
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Atomic classification
Shell occupancy
Neptunium in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 18 electrons
- N · n=4
- 32 electrons
- O · n=5
- 22 electrons
- P · n=6
- 9 electrons
- Q · n=7
- 2 electrons
- Electron configuration
- [Rn]7s2 5f4 6d1
- Electrons per shell
- 2 · 8 · 18 · 32 · 22 · 9 · 2
- Group
- not reported
- Period
- 7
- Block
- F
- Element category
- Actinide
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Physical and chemical properties
- Atomic mass
- [237.048172] u
- Standard state
- solid
- Density
- 20.25 g/cm³
- Melting point
- 917 K
- Boiling point
- 4,175 K
- Electronegativity
- 1.36 (Pauling)
- First ionisation energy
- 6.266 eV
- Oxidation states
- +6, +5, +4, +3
- Discovery
- 1940
Safety and periodic classification
Safety
Safe handling cannot be inferred from Neptunium's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Neptunium is in period 7 and the F block. Its direct neighbours by atomic number are Uranium and Plutonium. The recorded Pauling electronegativity is 1.36. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.