# Homework Help: Compounds and ions help please

1. Oct 4, 2016

### givemeknowledge

Hey,

So I've got a homework question which is gradually transforming by brain in to mashed potato!

Here it is..

Identify which of the following compounds contains ions and state the formal charges on the ions: NaCl, N2, MgO, AlCl3, and CO2.

Now, I'm not asking for someone to come in and give me the answer to all of them, I'm just after how I can find the answers, I just don't understand after a long time Googling..

I've had a crack and found that NaCl is ionic, but I just don't understand how to figure out the formal charge..

I'm at a loss, any help will be great - thank you!

2. Oct 4, 2016

### Staff: Mentor

Hint: octet rule-

By the way, please do not remove the homework template, but use it to set up your question.

3. Oct 4, 2016

### givemeknowledge

I've read about the octet rule but just can't join the two together, FML.

Okay I won't in future, I'm very new here.

4. Oct 4, 2016

### Staff: Mentor

Take NaCl as an example. What do you need to do to Na and Cl so that both follow the octet rule?

5. Oct 4, 2016

### givemeknowledge

Na needs to gain an electron (I think) and Cl needs to lose an electron to reach the nearest full shell

6. Oct 4, 2016

### givemeknowledge

So would I be right in thinking...

If N2 is 2 nitrogen atoms, and both have a charge of 3- does that give it a formal charge of 6-?

One thing that's confusing me.. The question says "the following compounds" yet N2 is not a compound... hmm

7. Oct 4, 2016

### Staff: Mentor

What is the electron configuration of Na and Cl?

Don't you have to determine if ir contains ions first?

What do you call a compound?

8. Oct 4, 2016

9. Oct 5, 2016

### Staff: Mentor

So, for Na and Cl, what is the simplest way to fulfill the octet rule?

Does N2 contain ions? Indeed, it is not strictly speaking a compound, but you can treat it as such for this question (actually, this gives you a hint as to whether it contains ions or not).

10. Oct 5, 2016

### Staff: Mentor

While N2 is technically not a compound, it is still a molecule - so it can either be ionic, or not.