Element 31 · Gallium (Ga)

Gallium Bohr model: diagram and electrons per shell

The gallium Bohr model shows a gallium atom (Ga) as a small nucleus with its electrons circling it in 4 shells: 2 in shell K, 8 in shell L, 18 in shell M and 3 in shell N. This page has a rotating 3D gallium Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the gallium Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of gallium (Ga), a simplified picture of a single gallium atom. Its nucleus holds 31 protons, and a neutral gallium atom has 31 electrons, arranged around it in 4 shells (2 in shell K, 8 in shell L, 18 in shell M and 3 in shell N).

Ga K · 21s² L · 82s² 2p⁶ M · 183s² 3p⁶ 3d¹⁰ N · 34s² 4p¹

Gallium Bohr model diagram

Bohr model diagram of gallium: a nucleus of 31 protons with 31 electrons on 4 shells, 2 in shell K, 8 in shell L, 18 in shell M and 3 in shell N, each ring labelled with its shell letter. — The gallium 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 and 3 in shell N).

Gallium electrons per shell

A neutral gallium atom has 31 electrons, one for each of its 31 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M and 3 in shell N.

Electrons in each shell of the gallium 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	3	32	4s² 4p¹

How the gallium Bohr model builds up, shell by shell

Watch the gallium 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 and 3 in shell N) as it forms.

Animation of the gallium Bohr model being built: a nucleus of 31 protons appears first, then each shell grows in around it and takes its electrons, giving 31 electrons on 4 shells (2 in shell K, 8 in shell L, 18 in shell M and 3 in shell N). — The gallium 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 and 3 in shell N. Protons are red, neutrons yellow and electrons blue.

How to draw the gallium Bohr model

Find the atomic number. Gallium has atomic number 31, so a neutral atom has 31 protons and 31 electrons.
Draw the nucleus. Put a circle in the centre and write Ga in it. The 31 protons sit there with the neutrons.
Draw the shells. Sketch 4 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 and 3 in shell N.
Check the total. 2 + 8 + 18 + 3 = 31, the atomic number, so every electron is accounted for.

Atomic data for the gallium Bohr model

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

Identity

Symbol: Ga
Atomic number: 31
Atomic mass: 69.7231 u
Family: Post-Transition Metals
Position: group 13, period 4
Block: p-block

Electron configuration

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹
Shorthand: [Ar] 3d¹⁰ 4s² 4p¹
Electrons per shell: 2, 8, 18, 3
Outer-shell electrons: 3 in shell N

Ionisation energies

I₁: 578.8
I₂: 1979.3
I₃: 2963
I₄: 6180

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

Atomic radii

Calculated (pm): 136
Empirical (pm): 130
Covalent (pm): 124
Van der Waals (pm): 187

Electronegativity and electron affinity

Electronegativity (Pauling): 1.81
Electron affinity (kJ/mol): 41

Oxidation states

Charges the element commonly takes in compounds.

Physical properties, abundance and history of gallium

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

Physical properties

Phase at room conditions: Solid
Appearance: Silver-white
Melting point: 29.76°C (302.9146 K)
Boiling point: 2399.85°C (2673 K)
Density: 5.91 g/cm³
Thermal conductivity (W/m·K): 28.1
Specific heat (J/g·K): 0.373
Molar heat capacity (J/mol·K): 25.86
Heat of fusion (kJ/mol): 5.59
Heat of vaporisation (kJ/mol): 270.3

Abundance

Earth's crust (mg/kg): 19
Oceans (mg/L): 0

Discovery

Discovered by: Lecoq de Boisbaudran
Year: 1875

Common compounds

Gallium arsenide AsGa
Gallium chloride Cl3Ga
Gallium Ga
Gallium nitrate GaN3O9
Gallium phosphide GaP
Gallium citrate C6H5GaO7
Gallium Citrate Ga-67 C6H5GaO7
Gallium bromide (GaBr3) Br3Ga

Compounds listed in the PubChem database.

Main isotopes of gallium

Isotopes of gallium share the same 31 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of gallium: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
66	–	9.304 h	β⁺
67	–	3.262 d	EC
69	60.108 %	stable	–
71	39.892 %	stable	–
72	–	14.025 h	β⁻
73	–	4.86 h	β⁻

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

More about gallium

Gallium on the periodic table – properties, isotopes, uses and the full gallium page.
Post-Transition Metals – all post-transition metal elements and their trends.
Bohr model of every element – the Bohr model of all 118 elements.