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
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
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.
Nearby elements
See the ionic charge of every element →