Element 13 · Aluminium (Al)
Aluminium Bohr model: diagram and electrons per shell
The aluminium Bohr model shows a aluminium atom (Al) as a small nucleus with its electrons circling it in 3 shells: 2 in shell K, 8 in shell L and 3 in shell M. This page has a rotating 3D aluminium Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.
Rotate the aluminium Bohr model in 3D
Drag to orbit, scroll to zoom.
This is a Bohr model of aluminium (Al), a simplified picture of a single aluminium atom. Its nucleus holds 13 protons, and a neutral aluminium atom has 13 electrons, arranged around it in 3 shells (2 in shell K, 8 in shell L and 3 in shell M).
Aluminium Bohr model diagram
Aluminium electrons per shell
A neutral aluminium atom has 13 electrons, one for each of its 13 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L and 3 in shell M.
| Shell | Shell number (n) | Electrons | Most it can hold (2n²) | Subshells |
|---|---|---|---|---|
| K | 1 | 2 | 2 | 1s2 |
| L | 2 | 8 | 8 | 2s2 2p6 |
| M | 3 | 3 | 18 | 3s2 3p1 |
How the aluminium Bohr model builds up, shell by shell
Watch the aluminium 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 and 3 in shell M) as it forms.
How to draw the aluminium Bohr model
- Find the atomic number. Aluminium has atomic number 13, so a neutral atom has 13 protons and 13 electrons.
- Draw the nucleus. Put a circle in the centre and write Al in it. The 13 protons sit there with the neutrons.
- Draw the shells. Sketch 3 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 and 3 in shell M.
- Check the total. 2 + 8 + 3 = 13, the atomic number, so every electron is accounted for.
Atomic data for the aluminium Bohr model
The numbers behind the aluminium Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).
Identity
- Symbol
- Al
- Atomic number
- 13
- Atomic mass
- 26.9815 u
- Family
- Post-Transition Metals
- Position
- group 13, period 3
- Block
- p-block
Electron configuration
- Full
- 1s2 2s2 2p6 3s2 3p1
- Shorthand
- [Ne] 3s2 3p1
- Electrons per shell
- 2, 8, 3
- Outer-shell electrons
- 3 in shell M
Ionisation energies
- I₁
- 577.5
- I₂
- 1816.7
- I₃
- 2744.8
- I₄
- 11577
- I₅
- 14842
- I₆
- 18379
- I₇
- 23326
- I₈
- 27465
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)
- 118
- Empirical (pm)
- 125
- Covalent (pm)
- 126
- Van der Waals (pm)
- 184
Electronegativity and electron affinity
- Electronegativity (Pauling)
- 1.61
- Electron affinity (kJ/mol)
- 41.762
Oxidation states
+3
Charges the element commonly takes in compounds.
Physical properties, abundance and history of aluminium
Bulk properties of aluminium, how common it is, who discovered it and some of its compounds.
Physical properties
- Phase at room conditions
- Solid
- Appearance
- Silvery gray metallic
- Melting point
- 660.32°C (933.47 K)
- Boiling point
- 2469.85°C (2743 K)
- Density
- 2.7 g/cm³
- Thermal conductivity (W/m·K)
- 237
- Specific heat (J/g·K)
- 0.897
- Molar heat capacity (J/mol·K)
- 24.2
- Heat of fusion (kJ/mol)
- 10.75
- Heat of vaporisation (kJ/mol)
- 284.1
Abundance
- Earth's crust (mg/kg)
- 82300
- Oceans (mg/L)
- 0.002
Discovery
- Year
- 1825
- Named by
- Humphry Davy
Common compounds
- Aluminum Al
- Aluminum Acetate C6H9AlO6
- Aluminum Chloride AlCl3
- Potassium Alum AlKO8S2
- Aluminum fluoride AlF3
- Aluminum bromide AlBr3
- Aluminum Lactate C9H15AlO9
- Cryolite AlF6Na3
Compounds listed in the PubChem database.
Main isotopes of aluminium
Isotopes of aluminium share the same 13 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.
| Mass number | Natural abundance | Half-life | Decay |
|---|---|---|---|
| 25 | – | 7.167 s | β⁺ |
| 26 | – | 717 ky | β⁺ |
| 27 | 100 % | stable | – |
| 28 | – | 2.245 min | β⁻ |
| 29 | – | 6.56 min | β⁻ |
| 30 | – | 3.62 s | β⁻ |
α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.
More about aluminium
- Aluminium on the periodic table – properties, isotopes, uses and the full aluminium page.
- Post-Transition Metals – all post-transition metal elements and their trends.
- Bohr model of every element – the Bohr model of all 118 elements.