In aluminum sulfide (Al2S3), the charges on the ions are determined by the oxidation states of the constituent elements.
Aluminum (Al) typically has an oxidation state of +3. Therefore, each aluminum ion (Al3+) carries a charge of +3. Since there are two aluminum ions in the formula Al2S3, the total positive charge contributed by aluminum ions is +6.
Sulfur (S), on the other hand, usually has an oxidation state of -2 in sulfide compounds. This means that each sulfide ion (S2-) carries a charge of -2. In Al2S3, there are three sulfide ions, contributing a total negative charge of -6.
To summarize, in aluminum sulfide (Al2S3):
- Each aluminum ion (Al) has a charge of +3.
- Each sulfide ion (S) has a charge of -2.
The balance of charges results in a neutral compound, as the total positive charge (+6) equals the total negative charge (-6).