Element 93 · Neptunium (Np)

Neptunium Bohr model: diagram and electrons per shell

The neptunium Bohr model shows a neptunium atom (Np) as a small nucleus with its electrons circling it in 7 shells: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q. This page has a rotating 3D neptunium Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the neptunium Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of neptunium (Np), a simplified picture of a single neptunium atom. Its nucleus holds 93 protons, and a neutral neptunium atom has 93 electrons, arranged around it in 7 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q).

Np K · 21s² L · 82s² 2p⁶ M · 183s² 3p⁶ 3d¹⁰ N · 324s² 4p⁶ 4d¹⁰ 4f¹⁴ O · 225s² 5p⁶ 5d¹⁰ 5f⁴ P · 96s² 6p⁶ 6d¹ Q · 27s²

Neptunium Bohr model diagram

Bohr model diagram of neptunium: a nucleus of 93 protons with 93 electrons on 7 shells, 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q, each ring labelled with its shell letter. — The neptunium Bohr model drawn flat: each ring is a shell, labelled with its letter, and every dot is an electron (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q).

Neptunium electrons per shell

A neutral neptunium atom has 93 electrons, one for each of its 93 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q.

Electrons in each shell of the neptunium Bohr model
Shell	Shell number (n)	Electrons	Most it can hold (2n²)	Subshells
K	1	2	2	1s²
L	2	8	8	2s² 2p⁶
M	3	18	18	3s² 3p⁶ 3d¹⁰
N	4	32	32	4s² 4p⁶ 4d¹⁰ 4f¹⁴
O	5	22	50	5s² 5p⁶ 5d¹⁰ 5f⁴
P	6	9	72	6s² 6p⁶ 6d¹
Q	7	2	98	7s²

How the neptunium Bohr model builds up, shell by shell

Watch the neptunium Bohr model come together: the nucleus first, then each shell in turn, from the innermost outwards, with its electrons joining the ring. The legend names every shell and counts its electrons, so you can read off the arrangement (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q) as it forms.

Animation of the neptunium Bohr model being built: a nucleus of 93 protons appears first, then each shell grows in around it and takes its electrons, giving 93 electrons on 7 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q). — The neptunium Bohr model built up in six seconds: the nucleus first, then each shell with its electrons, ending with 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q. Protons are red, neutrons yellow and electrons blue.

How to draw the neptunium Bohr model

Find the atomic number. Neptunium has atomic number 93, so a neutral atom has 93 protons and 93 electrons.
Draw the nucleus. Put a circle in the centre and write Np in it. The 93 protons sit there with the neutrons.
Draw the shells. Sketch 7 shells as rings around the nucleus. A shell holds at most 2n² electrons: 2 in the first, 8 in the second, 18 in the third and 32 in the fourth.
Place the electrons. Fill from the inside out: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 22 in shell O, 9 in shell P and 2 in shell Q.
Check the total. 2 + 8 + 18 + 32 + 22 + 9 + 2 = 93, the atomic number, so every electron is accounted for.

Atomic data for the neptunium Bohr model

The numbers behind the neptunium Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).

Identity

Symbol: Np
Atomic number: 93
Atomic mass: [237] u
Family: Actinides
Position: period 7 of the f-block
Block: f-block

Electron configuration

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f⁴ 6d¹
Shorthand: [Rn] 5f⁴ 6d¹ 7s²
Electrons per shell: 2, 8, 18, 32, 22, 9, 2
Outer-shell electrons: 2 in shell Q

Ionisation energies

I₁: 604.5

Energy to remove each electron in turn (kJ/mol). A sharp jump means the next electron comes from an inner shell.

Atomic radii

Empirical (pm): 175
Covalent (pm): 171

Electronegativity and electron affinity

Electronegativity (Pauling): 1.36
Electron affinity (kJ/mol): 45.85

Oxidation states

Charges the element commonly takes in compounds.

Physical properties, abundance and history of neptunium

Bulk properties of neptunium, how common it is, who discovered it and some of its compounds.

Physical properties

Phase at room conditions: Solid
Appearance: Silvery metallic
Melting point: 638.85°C (912 K)
Boiling point: 4173.85°C (4447 K)
Density: 20.45 g/cm³
Molar heat capacity (J/mol·K): 29.46
Heat of fusion (kJ/mol): 9.6
Heat of vaporisation (kJ/mol): 336

Discovery

Discovered by: Edwin McMillan
Year: 1940

Common compounds

Neptunium Np
Neptunium-237 Np
Neptunium-239 Np
Neptunium, isotope of mass 238 Np
Neptunium-233 Np
Neptunium-232 Np
Neptunium tetranitrate N4NpO12-4
Neptunium oxide (NpO2) NpO2-4

Compounds listed in the PubChem database.

Main isotopes of neptunium

Isotopes of neptunium share the same 93 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of neptunium: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
234	–	4.4 d	β⁺
235	–	396.1 d	EC, α
236	–	153 ky	EC, β⁻, α
237	–	2.144 My	α, SF, 30Mg
238	–	2.099 d	β⁻
239	–	2.356 d	β⁻, α

α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.

More about neptunium

Neptunium on the periodic table – properties, isotopes, uses and the full neptunium page.
Actinides – all actinide elements and their trends.
Bohr model of every element – the Bohr model of all 118 elements.