Gallium (Ga)
Element 31 · post-transition metal · group 13, period 4
Gallium is element 31, a post-transition metal in group 13 and period 4. Its electron configuration is [Ar] 3d10 4s2 4p1. That leaves 3 valence electrons in the outer shell, with the shells filling 2, 8, 18, 3. Losing its 3 valence electrons is the shorter route to a full shell, so it carries a charge of +3.
- 31 protons
- 3 valence e−
- +3
- p-block
Properties
| Atomic number | 31 |
|---|---|
| Symbol | Ga |
| Standard atomic weight | 69.723 u |
| Group | 13 |
| Period | 4 |
| Block | p-block |
| Category | post-transition metal |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1 |
| Noble-gas notation | [Ar] 3d10 4s2 4p1 |
| Electrons per shell | 2, 8, 18, 3 |
| Valence electrons | 3 |
| Common ionic charge | +3 |
| Electronegativity (Pauling) | 1.81 |
| Protons / electrons | 31 / 31 |
Electron configuration of gallium
Orbitals fill from the lowest energy upward. Writing that out for gallium gives 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1, which is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1 in plain text.
Everything up to Ar is the same as in that noble gas, so it is usually abbreviated to [Ar] 3d10 4s2 4p1. 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 | 6 | 6 |
| 3d | 10 | 10 |
| 4s | 2 | 2 |
| 4p | 1 | 6 |
Gallium ion charge
Gallium 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 gallium have?
Gallium has 3 valence electrons. For a main-group element the count is the group number minus 10, and gallium is in group 13.
What is the electron configuration of gallium?
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1, or [Ar] 3d10 4s2 4p1 written from the previous noble gas. Orbitals fill lowest energy first.
What is the charge of gallium?
Gallium 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 gallium have?
A neutral gallium atom has 31 protons and 31 electrons. Its standard atomic weight is 69.723, so the most common isotope has about 39 neutrons.
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