A compound contains gallium ions and sulfide ions.
The table shows the numbers of protons and electrons in each ion.
| ion | number of protons | number of electrons |
|---|---|---|
| gallium ion | 31 | 28 |
| sulfide ion | 16 | 18 |
A student suggests that the formula of the compound is Ga3S2\mathrm{Ga_3S_2}Ga3S2.
Explain whether the student's formula is correct.
119 exam-style questions on Edexcel GCSE Chemistry 2.3 Ionic bonding, covering 2.3.1 Ions and the formation of ionic bonds, 2.3.2 Naming and deducing formulae of ionic compounds, and 2.3.3 Giant ionic lattices. Each one has a worked solution and a mark scheme showing where the marks go.