Oxidation #

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Ashley Lopez 3J
Posts: 90
Joined: Wed Sep 30, 2020 10:06 pm

Oxidation #

Postby Ashley Lopez 3J » Sun Dec 06, 2020 10:17 pm

How do we find the oxidation numbers? I am still a bit confused on how we find them and my PLF session talked about it, but very quickly and I still don't fully get it.

Izamary Marquez 2H
Posts: 94
Joined: Wed Sep 30, 2020 9:44 pm

Re: Oxidation #

Postby Izamary Marquez 2H » Sun Dec 06, 2020 10:25 pm

It helps me to look at the individual charges and then the sumo them! The oxidation number refers to the charge on the ion. In addition to this question, are there trends with oxidation numbers that make them easier to memorize?

Brennan McGurrr 3C
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Joined: Wed Sep 30, 2020 9:47 pm

Re: Oxidation #

Postby Brennan McGurrr 3C » Sun Dec 06, 2020 10:26 pm

Oxidation number means the charge that an ion forms during bonding. For example in NaCl, Na has an oxidation number of +1 and Cl has an oxidation number of -1. However, transition metals often have several possible oxidation numbers. Using a roman numeral after its name indicates which one. Anions can only form ions with one oxidation state, so they are used to determine the oxidation state of a transition metal in a coordinate compound. For example in [Co(NH3)5Cl]2-, the overall complex ion has a charge of -2. So the oxidation number of all the atoms in the ion must add to -2. NH3 is a neutral compound so it won't affect it. Chlorine always has a -1 oxidation number, so the oxidation state of cobalt must be +3.

Jose Miguel Conste 3H
Posts: 91
Joined: Sat Oct 03, 2020 12:15 am

Re: Oxidation #

Postby Jose Miguel Conste 3H » Sun Dec 06, 2020 10:29 pm

unfortunately you kind of have to memorize the common oxidation numbers in order to find oxidation numbers of others, some I can grab at the top of my head it nitrite (no2-), nitrate (no3-), group elements from group 17 will always be -1, group elements from element 1 will always be +1, and group elements from group 2 will always be -2, etc etc.

Joanna Huang
Posts: 92
Joined: Wed Sep 30, 2020 9:40 pm

Re: Oxidation #

Postby Joanna Huang » Sun Dec 06, 2020 10:31 pm

1) The oxidation number of a free element is 0
2) The number for the cation/anion is usually just their charge
3) the number for H is usually +1
4) the oxidation number for O is -2 unless it's in peroxides

That's what I have so far :D

Nick Pascua 2L
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Joined: Wed Sep 30, 2020 9:43 pm
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Re: Oxidation #

Postby Nick Pascua 2L » Sun Dec 06, 2020 10:32 pm


To find oxidation numbers, you need to do a little bit of math. In an overall case where a compound is considered neutral, charges have to be equal to 0.

For example, if we have CO2 (a neutral atom with no overall charge), the overall charge has to equal 0. In many cases in 14A like Coordination Compounds, the metal is what we need to find. Since we know Oxygen in CO2 is typically 2- (as stated as a common oxidation number), we can do the math to find Carbon (lets let Carbon be X).
This is the basic method in finding oxidation numbers.
Here is an attached link to calculating basic oxidation numbers if you're still confused! Good luck!

Michael Cardenas 3B
Posts: 56
Joined: Wed Sep 30, 2020 9:34 pm

Re: Oxidation #

Postby Michael Cardenas 3B » Sun Dec 06, 2020 10:49 pm

To find the oxidation number of the central metal ion you have to compare the overall charge of the compound(ie. neutral,2-,3+) then you have to compare it with the known charges of the ligands. Whatever the difference between the two numbers is the oxidation number of the central metal atom.

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