The Student Room Group

Oxidation states

Okay, this might be obvious to some of you but I’m a little confused about knowing the difference between a neutral compound and a polyatomic charge ion.

I understand what must happen for a redox reaction to occur and the rules that are used to calculate oxidation numbers but looking at the letters, how do I know which are neutral and which are not?

I hope this makes sense of what I'm asking.

For example: Ca²0-² is a neutral compound due to their oxidation state=0

But how would I know CO₃²- be is a polyatomic ion without asking online?

Thank you
(edited 2 months ago)
Original post by KingRich
Okay, this might be obvious to some of you but I’m a little confused about knowing the difference between a neutral compound and a polyatomic charge ion.
I understand what must happen for a redox reaction to occur and the rules that are used to calculate oxidation numbers but looking at the letters, how do I know which are neutral and which are not?
I hope this makes sense of what I'm asking.
Thank you
the overall molecule is neutral in the sense its charge is 0 ie h20, methane. a polyatomic charge ion is one that doesn't have a charge that is basically something other than 0. examples is a sulphate ion- so42-, nh4+ ammonium ions. stuff like that.
Reply 2
Original post by jacksmith23
the overall molecule is neutral in the sense its charge is 0 ie h20, methane. a polyatomic charge ion is one that doesn't have a charge that is basically something other than 0. examples is a sulphate ion- so42-, nh4+ ammonium ions. stuff like that.
So, the key difference is whether it is presented as a postive or negative charged ion vs no charge?

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