Question

What is the oxidation number of a Group VIIA element in a compound?

Answer 1

The oxidation number of a Group 7 element depends on the compound it is in.

Explanation:

The most common oxidation number for Group 7 elements is -1, as in `"HF"`, `"CaCl"_2`, `"NaBr"`, and `"KI"`.

`"F"` is the most electronegative element in the Periodic Table. It isn't going to give up its electrons.

Its oxidation number in compounds is always -1.

But the other Group 7 elements can have various oxidation states.

For example, `"Cl"` forms compounds with all the oxidation states except +2:

• +1 — in `"NaClO"`
• +3 — in `"NaClO"_2`
• +4 — in `"ClO"_2`
• +5 — in `"KClO"_3`
• +6 — in `"Cl"_2"O"_6`
• +7 — in `"KClO"_4`

`"Br"` and `"I"` form compounds with all the above oxidation states except +6 (some of these compounds are unstable).