What is the charge on the chromium ion in the ionic compound CrCl3?
The Correct Answer and Explanation is:
Correct Answer: +3
Explanation:
To determine the charge on the chromium ion in the ionic compound CrCl₃, follow these steps:
- Understand the compound structure:
- CrCl₃ is an ionic compound made of chromium (Cr) and chlorine (Cl).
- In ionic compounds, the total charge is neutral, meaning the positive charges must balance the negative charges.
- Determine the charge of chlorine:
- Chlorine is a halogen in Group 17 of the periodic table, and it commonly forms ions with a charge of -1 (Cl⁻) because it gains one electron to achieve a stable octet configuration.
- Set up the equation for neutrality:
- CrCl₃ has one chromium ion and three chloride ions. The total negative charge from the chloride ions is:
[
3 \times (-1) = -3
] - For the compound to be neutral, the chromium ion must have a positive charge of +3 to balance the -3 from the chlorides.
- Confirm the charge:
- Chromium in this compound is in its +3 oxidation state, written as Cr³⁺.
- This is consistent with the formula CrCl₃, where the ratio of ions ensures overall neutrality.
- Verify with naming conventions:
- CrCl₃ is named chromium(III) chloride, with the Roman numeral III indicating the +3 charge of chromium.
- General principle:
- Transition metals like chromium can exhibit multiple oxidation states. The specific charge is determined based on the anion charges and the need for electrical neutrality in the compound.
In summary, the chromium ion in CrCl₃ has a charge of +3, balancing the three chloride ions with a charge of -1 each. This maintains the neutrality of the compound.