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Oxidation Numbers

Posted: Fri Feb 10, 2017 8:05 pm
by Emily_Bennett_3C
When a question asks "indicate the initial and final oxidation numbers", how do you go about finding those numbers?

Re: Oxidation Numbers

Posted: Fri Feb 10, 2017 8:23 pm
by kara_kremer_2N
All elements have a zero oxidation charge

All molecules have the charge specified (some you may have to memorize)

Group 1 elements are always +1

Group 2 elements are usually +2

Chalcogens are usually -2

Halogens are usually -1

The charges of the ions have to equal the charge of the total molecule

Re: Oxidation Numbers

Posted: Fri Feb 10, 2017 8:53 pm
by Marie_Rhoads_2C
Some other good things to know about oxidation numbers is that O is almost always a -2 charge when it's with other elements in a compound like SeO42-. For this one the O charges will add up to -8, so the Se must have an oxidation number of +6 to make the overall charge -2. Also, elements in their natural state will have an oxidation number of 0. This still applies for diatomic molecules, so Br2 has an oxidation number of 0.