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Can't get my head around this Redox

So in NO3- N has an oxidation of +5
I was initially confused because I thought NO3- had an extra electron since it was a negative ion. So I thought that since normal 03 would be -6 an extra electron must mean that it will be a -7 and so N must be +6. +6 +-7 = -1

But having thought about it the overall charge is -1 not just for the 03 so if O3 is -6 then N has to be +5 for the overall charge to be -1

What I don't get is is why NO3 is 1- in the first place. Does nitrogen not fill its shell? Does oxygen not form a double bond?

I thought ions had extra or less electrons. So why is nh4 a nh4+ ion if it has 8 electrons and has gained 3. Where has it lost an electron.

I am really confused. Any help is appreciated.

Thanks!

(edited 8 years ago)

Reply 1

Pigster

This should help:

http://www.kentchemistry.com/links/bonding/lewisdotstruct.htm

Reply 2

littleheron

Original post by Pigster

This should help:

http://www.kentchemistry.com/links/bonding/lewisdotstruct.htm

Very useful thanks. But it still doesn't answer my question. So an example he used is H30+ . Is it +1 because the oxygen covalent shares 3 electrons with the 3 hydrogen atomsand has 1 lone pair so 5 electrons are used. Has it lost the extra electron to become an ion? Oxygen has 6 electrons in its outer shell

(edited 8 years ago)

Reply 3

Pigster

H3O+

Total number of p+: 3x1 + 8 = 11
Total number of e-: 10
+1 charge

Water has 2x lone pairs and 2x standard covalent bonds i.e. 2x shared pairs.
H3O+ has 1x lone pair, 2x covalent bonds and 1x dative covalent bond to an H+

If you tried to add a third H atom, there would be 9e- in O's outer shell. Not good.