Write the chemical formula for an ionic compound composed of each pair of ions.
1. the calcium ion and the oxygen ion
2. the 2+ copper ion and the sulfur ion
3. the 1+ copper ion and the sulfur ion
The correct answer and explanation is:
- Calcium ion (Ca²⁺) and Oxygen ion (O²⁻):
The chemical formula for the ionic compound formed by the calcium ion and oxygen ion is CaO.
- The calcium ion has a charge of 2+ (Ca²⁺) and the oxygen ion has a charge of 2− (O²⁻).
- The charges of the ions balance each other out because they are of equal magnitude.
- Therefore, one calcium ion will combine with one oxygen ion to form the neutral compound CaO.
- Copper (II) ion (Cu²⁺) and Sulfur ion (S²⁻):
The chemical formula for the ionic compound formed by the copper (II) ion and the sulfur ion is CuS.
- The copper (II) ion has a charge of 2+ (Cu²⁺) and the sulfur ion has a charge of 2− (S²⁻).
- As with the calcium and oxygen ions, the charges of the copper (II) and sulfur ions are balanced.
- Therefore, one copper (II) ion will combine with one sulfur ion to form the neutral compound CuS.
- Copper (I) ion (Cu⁺) and Sulfur ion (S²⁻):
The chemical formula for the ionic compound formed by the copper (I) ion and the sulfur ion is Cu₂S.
- The copper (I) ion has a charge of 1+ (Cu⁺) and the sulfur ion has a charge of 2− (S²⁻).
- To balance the charges, two copper (I) ions are needed to counteract the 2− charge of one sulfur ion.
- Therefore, two Cu⁺ ions combine with one S²⁻ ion to form the neutral compound Cu₂S.
In each case, the goal is for the positive and negative charges to balance out to create a neutral compound. The ratio of the ions in the compound depends on their respective charges, which determines how many of each ion are needed to neutralize the overall charge of the compound.