Aluminium (Al)
Element 13 · post-transition metal · group 13, period 3
Aluminium is element 13, a post-transition metal in group 13 and period 3. Its electron configuration is [Ne] 3s2 3p1. That leaves 3 valence electrons in the outer shell, with the shells filling 2, 8, 3. Losing its 3 valence electrons is the shorter route to a full shell, so it carries a charge of +3.
- 13 protons
- 3 valence e−
- +3
- p-block
Aluminium Lewis dot structure
Aluminium has 3 valence electrons, so its Lewis symbol carries 3 dots: three single dots. The dots go one to a side before any of them pair up, so the unpaired ones show exactly how many bonds the atom tends to form. The ion has given those electrons away, which is why it is drawn in brackets with none.
Draw it in the Lewis structure generator →
Properties
| Atomic number | 13 |
|---|---|
| Symbol | Al |
| Standard atomic weight | 26.982 u |
| Group | 13 |
| Period | 3 |
| Block | p-block |
| Category | post-transition metal |
| Electron configuration | 1s2 2s2 2p6 3s2 3p1 |
| Noble-gas notation | [Ne] 3s2 3p1 |
| Electrons per shell | 2, 8, 3 |
| Valence electrons | 3 |
| Common ionic charge | +3 |
| Electronegativity (Pauling) | 1.61 |
| Protons / electrons | 13 / 13 |
Electron configuration of aluminium
Orbitals fill from the lowest energy upward. Writing that out for aluminium gives 1s2 2s2 2p6 3s2 3p1, which is 1s2 2s2 2p6 3s2 3p1 in plain text.
Everything up to Ne is the same as in that noble gas, so it is usually abbreviated to [Ne] 3s2 3p1. The part outside the bracket is what does the chemistry.
| Subshell | Electrons | Capacity |
|---|---|---|
| 1s | 2 | 2 |
| 2s | 2 | 2 |
| 2p | 6 | 6 |
| 3s | 2 | 2 |
| 3p | 1 | 6 |
Aluminium ion charge
Aluminium commonly forms ions with a charge of +3.
It has 3 valence electrons, so it is 5 short of a full octet and 3 above an empty outer shell. An atom takes whichever route is shorter, which is why the charge comes out as it does.
Common questions
What is the Lewis dot structure of aluminium?
The symbol Al with 3 dots, one for each valence electron: three single dots. Dots go one to a side before any pair up, the same way electrons fill separate orbitals before sharing one. The Al3+ ion is drawn in brackets with no dots, because it has lost them.
How many valence electrons does aluminium have?
Aluminium has 3 valence electrons. For a main-group element the count is the group number minus 10, and aluminium is in group 13.
What is the electron configuration of aluminium?
1s2 2s2 2p6 3s2 3p1, or [Ne] 3s2 3p1 written from the previous noble gas. Orbitals fill lowest energy first.
What is the charge of aluminium?
Aluminium commonly forms ions with a charge of +3. With 3 valence electrons it is 5 short of an octet and 3 above an empty shell, so it takes whichever route is shorter.
How many protons, electrons and neutrons does aluminium have?
A neutral aluminium atom has 13 protons and 13 electrons. Its standard atomic weight is 26.982, so the most common isotope has about 14 neutrons.
Aluminium in Lewis structures
What the configuration above means in practice. Aluminium brings 3 valence electrons to it, and the working there starts by counting exactly that.
Nearby elements
See the ionic charge of every element →