## Number of electrons

Brandon Mo 4K
Posts: 70
Joined: Fri Sep 28, 2018 12:15 am

### Number of electrons

How do we determine the number of electrons in the oxidation and reduction half-reactions?

Kevin ODonnell 2B
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

### Re: Number of electrons

In half reactions we just find the sum of the two halves (the reduction half-reaction + the oxidation half-reaction). First make sure all of the equations are balanced. Make sure in molecule compounds as well that you are taking note of the sign. For example, let's pretend that FeO2-2 is a thing. We know O has a charge of -2 and -2 * 2 atoms = -4 charge, so we can deduce Fe has a initial charge of +2, and if it is oxidized we will see that it has a +3 charge on the product side.
As far as half reactions go I will attach an easy example:
Attachments

Bruce Chen 2H
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

### Re: Number of electrons

We want to balance the number of electrons on both sides. In order to do this, we must add electrons in the half reactions. They should cancel out when added.

204929947
Posts: 76
Joined: Fri Apr 06, 2018 11:03 am

### Re: Number of electrons

In adittion, how would you find out the oxidation number of an element??

Celine Cheng 1H
Posts: 33
Joined: Fri Sep 28, 2018 12:21 am
Been upvoted: 1 time

### Re: Number of electrons

For the oxidation numbers question, you generally want to look at the charge of the element/compound. The sum of the oxidation numbers of the elements in a compound should equate to the compound's overall charge. There are some specific rules for finding oxidation numbers of certain elements, which you can find here: https://www.khanacademy.org/science/che ... ion-number

Jocelyne Milke 1G
Posts: 73
Joined: Fri Sep 28, 2018 12:25 am

### Re: Number of electrons

you can find the oxidation numbers using the periodic table