I have a question which asks...

What is the Oxidation number of Nitrogen in Cu(NO3)2
I know the answer is 5+ but how do you get that??

Cu= 2+
O= 2- (Theres 3 of them so -2x3=-6...then, theres a two out of the brackets so 6- x 2 =-12)
+2 - (-12)= -10? And then what?
I think my method is wrong. :/ It's really frustrating and i've been at the same question for over an hour now.

See your third post above.

Finding the oxidation number of an element can be tricky, but there are some rules you can follow to determine it. Let's break it down step by step:

1. Start with the known oxidation numbers: In this case, you mentioned that Cu has a +2 oxidation number and O has a -2 oxidation number.

2. Identify the total charge of the compound: In Cu(NO3)2, each NO3 group has a net charge of -1 because O has a -2 charge and there are three of them. So, two NO3 groups will have a total charge of -2.

3. Determine the oxidation number of Cu: Since the overall charge of the molecule is neutral (0), the sum of the oxidation numbers of all atoms must add up to zero. Let's represent the oxidation number of Nitrogen as x. Therefore,
(+2) + (2x) + (-2) + (-2) = 0

4. Solve for x: Adding up all the oxidation numbers gives us: +2 + 2x - 2 - 2 = 0. Simplifying the equation, we have 2x - 2 = 0.

5. Solve for x: Adding 2 to both sides of the equation, we get 2x = 2. Dividing both sides by 2, we find x = 1.

Therefore, the oxidation number of nitrogen (N) in Cu(NO3)2 is +1.

It seems like you had some confusion in your calculations. Remember to consider the total charge of the compound and balance the equation properly to find the correct oxidation number.