Oxidation state

[rasen58]

What is the oxidation state of the polyatomic ion in the compound Mg(NO₃)₂

 

A. +2

B -2

C -1

D +5

E +6

 

The polyatomic ion is NO3, and I already knew the oxidation state of that nitrate is -1, so I thought the answer was actually +5.

How is the oxidation state even a positive number and how is it +5 because NO3 is an anion, so it should be negative anyway.

[hypervalent_iodine]

The question seems to be a bit odd. A polyatomic ion has a charge which results from the sum of the charges of its constituents, but I wouldn't call that an oxidation state. You have gotten the answer of +5 from the nitrogen, so I assume that's what you are talking about and what it is asking for? Positive oxidation states come from a loss of electrons (i.e. an oxidation) and they are perfectly common. How did you come to +5 as an answer if you don't know how to get there?

[rasen58]

Sorry, I worded my question wrong.

I meant the actual answer is +5, but I thought it was just -1

So why is it +5?

[rktpro]

Charge of a polyatomic ion is defined. You must understand the difference between charge and oxidation number(not oxidation state, to be precise).Read definition, the charge an atom would aquire if all the covalent bonds of it in a bonded state are cleaved heterolytically, taking account of electronegativities.

Edited March 13, 2014 by rktpro