Is that PF6^-?
F is in group VIIA (or 17) and has an oxidation state of -1. That makes -6 total for F. To leave -1 on the ion, P must have an oxidation state of +5. Check my work.
Here is a site that contains some very simple rules for assigning oxidation states.
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assign oxidation numbers to
PF-6(aq)
1 answer
5 answers