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Carbonate ion

Some people are saying that a carbonate ion has the formula CO3^2-, but some people say it’s only got a single -ve charge.
Can someone please tell me which one is right, thanks!
CO3^2- is the correct one
Reply 2
Avatar for Mavs04
Mavs04
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Original post by golgiapparatus31
CO3^2- is the correct one

Thanks!
Please cd u explain why cos if carbon has 4e- in its outer shell already, and it gains 1 from each covalent bond of the 3 oxygens - then I don’t get why it needs to gain 2 more electrons from elsewhere, when it only needs one more?
Original post by Mavs04
Thanks!
Please cd u explain why cos if carbon has 4e- in its outer shell already, and it gains 1 from each covalent bond of the 3 oxygens - then I don’t get why it needs to gain 2 more electrons from elsewhere, when it only needs one more?

See structure of carbonate ion
https://courses.lumenlearning.com/introchem/chapter/carbon-oxides-and-carbonates/

The structure can be thought of as an oxygen atom forming a double bond to a carbon atom, and 2 oxygen atoms with a negative charge (O-) forming a single bond to the carbon atom
Reply 4
Avatar for Mavs04
Mavs04
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Original post by golgiapparatus31
See structure of carbonate ion
https://courses.lumenlearning.com/introchem/chapter/carbon-oxides-and-carbonates/

The structure can be thought of as an oxygen atom forming a double bond to a carbon atom, and 2 oxygen atoms with a negative charge (O-) forming a single bond to the carbon atom


Ahhh ok that makes sense thanks
Original post by Mavs04
Thanks!
Please cd u explain why cos if carbon has 4e- in its outer shell already, and it gains 1 from each covalent bond of the 3 oxygens - then I don’t get why it needs to gain 2 more electrons from elsewhere, when it only needs one more?

This logic fails because oxygen needs to form double bonds to gain an octet configuration, so each oxygen atom needs to contribute 2 electrons to carbon. So 3 oxygen atoms would contribute 6, which is 2 too much. That's where the extra electrons come in. 2 oxygen atoms gain 1 electron each, so now they only need for form a single bond, hence the 3 oxygens contribute 4 electrons to the carbon which works out.

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