[Guest]

On my chemisty homework worksheet I have to give the most likely oxidation number / charge for some elements by using a periodic table. How do I do this??

Thanks

[Guest]

On my chemisty homework worksheet I have to give the most likely oxidation number / charge for some elements by using a periodic table. How do I do this??

Thanks

It's been a while since Chem 111 but I think the oxidation number has something to do with the valance elctrons. Maybe not though, but it would be a good place to start reading in your book. Or just Google it.

[Yoruichi-san]

Elements or elements in compounds? For pure elements the oxidation number is 0. The oxidation number for any compound is the net charge on that compound, which for neutral compounds is 0.

For the individual elements in compounds, the method is usually:

Some elements are determined by the group #. In order of priority: Group 1, the alkali metals (first column of the periodic table) elements are +1, group 2, the alkaline earth metals, is +2. Oxygen is usually -2. Halogens (group 7) are usually -1.

Then for the remaining elements, you add up the oxidation numbers of the elements you know, then subtract that from the net oxidation number of the compound. For example:

H₂SO₄ (sulfuric acid...yummy )

Net is 0

Each H is +1

Each O is -2

S is unknown, call its oxidation number x

You have 2 H's and 4 O's, so 2*(1)+4*(-2)+x=0. -> 2-8+x=0 -> x=6

I was a TA for general chemistry once...this feels familiar ;P

[Guest]

Thanks Yoruichi-san, that helped a lot!