Memorizing oxidation numbers

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Mrudula Akkinepally
Posts: 105
Joined: Wed Sep 30, 2020 9:31 pm

Memorizing oxidation numbers

Postby Mrudula Akkinepally » Sat Nov 14, 2020 10:50 pm

Hi! I was wondering if we needed to memorize oxidation numbers for any elements to prepare for the midterm or if they will be given to us on the midterm as needed?

Shreya Patel- 2D
Posts: 96
Joined: Wed Sep 30, 2020 10:01 pm

Re: Memorizing oxidation numbers

Postby Shreya Patel- 2D » Sat Nov 14, 2020 11:30 pm

There is no typical rule, but this link kind of helped me remember how to find oxidation number: ... a-compound
Hope that helps!

Tae Pasawat 2A
Posts: 65
Joined: Tue Oct 06, 2020 12:16 am

Re: Memorizing oxidation numbers

Postby Tae Pasawat 2A » Sat Nov 14, 2020 11:55 pm

The oxidation numbers can be calculated by looking at the periodic table! The number of e- it loses or gains will be its oxidation number. For example, if oxygen needs to gain 2e- to complete its octet, its oxidation number will be -2.
You can also calculate the oxidation number of an element by looking at the oxidation number of other elements and deduce from there. For example NO3-. The overall molecule is negative, and we know that oxygen has a -2 charge. So since there are two oxygen atoms, this gives us a -4 charge. Since the molecule has a negative 1 charge, we know that nitrogen is +3.

Sydney Jensen 3L
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Joined: Wed Sep 30, 2020 10:03 pm
Been upvoted: 1 time

Re: Memorizing oxidation numbers

Postby Sydney Jensen 3L » Sun Nov 15, 2020 1:35 pm

On the periodic table, the different groups can help one determine the oxidation numbers. For example, oxygen is in group 16, which is two away from 18. At group 18, those elements have the full octet of electrons, hence the 18 for 8 electrons. In group 16, there are 6 valence electrons, and they need two more for the octet, so the oxidation number would be negative 2.

Veeda Khan 2E
Posts: 52
Joined: Wed Sep 30, 2020 10:00 pm

Re: Memorizing oxidation numbers

Postby Veeda Khan 2E » Sun Nov 15, 2020 1:49 pm

As everyone said before, as long as you know how many electrons a molecule has in it's outmost shell, you'll be able to figure out oxidation numbers.

Emily Jacobo 1C
Posts: 90
Joined: Wed Sep 30, 2020 9:37 pm

Re: Memorizing oxidation numbers

Postby Emily Jacobo 1C » Sun Nov 15, 2020 6:30 pm

I was confused on this too, and looking for good tips to memorize. So essentially knowing the number of valence electrons will help you determine the oxidation number for the element?

Nick P 3D
Posts: 98
Joined: Wed Sep 30, 2020 9:42 pm

Re: Memorizing oxidation numbers

Postby Nick P 3D » Sun Nov 15, 2020 6:45 pm

The easiest way I have found to do this is using the groups of the periodic table. Knowing that in group 18 an atom is full, how many groups away it is tells you how many electrons it will need, basically its oxidation number.

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