Is neptunium a metal?

Yes. Neptunium is a metal, classified as an actinide on the periodic table.

How many protons does neptunium have?

Neptunium has 93 protons. Its atomic number is 93, which is also the number of electrons in a neutral atom of neptunium.

What group and period is neptunium in?

Neptunium is in period 7 of the periodic table. As an actinide in the f-block, it sits in a separate row below the main table and has no standard group number.

What is the atomic mass of neptunium?

The atomic mass of neptunium is 237 u (unified atomic mass units).

Element 93

Neptunium (Np)

Actinide · Period 7 · f-block

Neptunium (Np) is element 93 of the periodic table, an actinide in period 7 (f-block) with an atomic mass of 237 and is a solid at standard conditions.

At a glance

Atomic number: 93
Symbol: Np
Atomic mass: 237 u
Category: Actinides
Period: 7
Block: f-block
Phase at STP: solid

Electron structure

Electron configuration: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f4 6d1 7s2
Shorthand configuration: [Rn] 5f4 6d1 7s2
Electrons per shell: 2, 8, 18, 32, 22, 9, 2
Oxidation states: +2, +3, +4, +5, +6, +7

Physical properties

Melting point: 917 K (643.85 °C)
Boiling point: 4,273 K (3,999.85 °C)
Density: 20.45 g/cm³
Phase: solid

Atomic properties

Electronegativity (Pauling): 1.36
Atomic radius: 155 pm
Covalent radius: 190 pm
First ionization energy: 605 kJ/mol
Electron affinity: 46 kJ/mol

Notable isotopes

Notable isotopes of Neptunium: mass number, atomic mass, natural abundance, and stability.
Isotope	Mass	Abundance	Stability
Np-237	237.04817	-	Half-life 2.14 million years

Common uses

Neutron detection
Weapons research
Spacecraft power

Discovery

Year: 1940
Discovered by: Edwin McMillan, Philip Abelson
Country: USA

Frequently asked questions

Is neptunium a metal?: Yes. Neptunium is a metal, classified as an actinide on the periodic table.
How many protons does neptunium have?: Neptunium has 93 protons. Its atomic number is 93, which is also the number of electrons in a neutral atom of neptunium.
What group and period is neptunium in?: Neptunium is in period 7 of the periodic table. As an actinide in the f-block, it sits in a separate row below the main table and has no standard group number.
What is the atomic mass of neptunium?: The atomic mass of neptunium is 237 u (unified atomic mass units).

Keep exploring

Neptunium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.