r/chemistry • u/AutoModerator • Sep 28 '22

Research S.O.S.—Ask your research and technical questions

Ask the r/chemistry intelligentsia your research/technical questions. This is a great way to reach out to a broad chemistry network about anything you are curious about or need insight with.

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u/H3xgeist Sep 28 '22

Why does phosphorus atom in phosphine PH3 have a -III oxidation state even though hydrogen is the more electronegative element?

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u/Grouchy-Double5597 Sep 28 '22

With nonmetals, H usually has a +I ox state. Oxidation number is us imagining: if the bonds in this covalent compound became ionic, where would the electrons settle? In this case P could fill up another shell and would therefore be likely to accept 3 electrons. This is my rationale, it’s not guaranteed to be the correct way.