How do you find a oxidation number?

Answer 1

Finding the oxidation number of an atom often requires you to use certain atoms as references. Oxygen and hydrogen are the most common examples. Almost all the time, hydrogen has an oxidation number of +1, and oxygen -2.

The sum of all oxidation numbers is equal to the charge on a given chemical species. Therefore, you can use these known oxidation numbers and the charge to deduce the other oxidation numbers.

Take chromate for example. Chromate has the chemical formula CrO42-. The charge on this species is -2. There are four oxygen atoms, each with an oxidation number of -2. Therefore, their combined effect is -8. The chromium atom must have an oxidation number that, when added to -8, will give the charge on the ion, -2. Therefore, chromium has an oxidation number of +6 in this case.

A similar approach can be used on a wide variety of molecules and ions.

Answer 2

Use oxygen at '-2' as the standard.

However, oxygen can vary, but initially use '-2'

So why is potassium permangate (VII) have the 'VII/7' in the name . It is the oxidation number of the manganese.

How do we gert there.

The formula is KMnO4

So there are four oxygens each at '-2' then overall the oxygen component is 4 x -2 = -8

Since the K is a Group '1' metal its oxidation is K^+ = +1

So creating a little sum,

+1 + Mn - 8 = 0 (Zero because it is a neutral molecule)

Hence

Mn - 7 = 0

Hence Mn = 7 ( 'VII' latin numerals are used for oxidation numbers).

NB Oxidation number refers to the numbers of electrons, of a given atom, involved in the bonding process.

NNB Sulphur has several oxidation numbers. They are: -

-2 in H2S

0 in elemental sulphur

+2 in SCl2

+4 in SO2

+6 in SO3 / H2SO4

Answer 3

To find the oxidation number of an element in a compound, you can use the rules of oxidation numbers. In general, elements in their elemental form have an oxidation number of 0, and in compounds, the sum of all oxidation numbers is equal to the overall charge of the compound. Oxidation numbers can also be determined based on electronegativity and the specific rules for different elements.