Answer:
Al³⁺, S²⁻; Al₂S₃
Explanation:
Al is a metal, so it loses its three valence electrons in a reaction to form Al³⁺ ions.
S is a nonmetal. It needs two more electrons to complete its octet, so it tends to form S²⁻ ions.
We can use the criss-cross method to work out the formula of the compound.
The steps are
- Write the symbols of the anion and cation.
- Criss-cross the numbers of the charges to become the subscripts of the other ion.
- Write the formula with the new subscripts.
- Divide the subscripts by their highest common factor.
- Omit all subscripts that are 1.
When we use this method with Al³⁺ and S²⁻, the formula for the compound formed becomes Al₂S₃ .
