Question

hexavalent chromium bonds with fluorine to form an ionic compound. whats the chemical formula and name for this compound using the stock system?
a) crf₆, chromium(vi) hexafluoride
b) cr₂f₆, chromous hexafluoride
c) cr₂f₆, chromium(vi) hexafluoride
d) crf₆, chromic fluoride

Explanation:

1. Determine the charges: Hexavalent chromium means Cr has a +6 charge. Fluorine (F) in ionic compounds has a -1 charge.
2. Balance charges: To balance the +6 charge of Cr, we need 6 F⁻ ions (since 6×(-1) = -6, and +6 + (-6) = 0). So the formula is CrF₆.
3. Stock system naming: The metal is chromium, and its oxidation state is +6 (indicated by Roman numeral VI), and the anion is fluoride (from fluorine). So the name is chromium(VI) hexafluoride. Option B has an incorrect formula (Cr₂F₆ would imply Cr has +3 charge, not +6), option C also has incorrect formula, and option D has incorrect name (doesn't use Stock system with VI and uses wrong anion name "fluoride" instead of "hexafluoride" for the polyatomic-like anion here).

Answer:

A) CrF₆, chromium(VI) hexafluoride