oxidation

[Michelle Argueta 1E]

how do you determine the oxidation number of an ion ?

[Mrinalini Mishra 2L]

Hi! To determine oxidation, you have to make an equation of the oxidation states you know already and solve for the oxidation state you don't know. For example, in ClO4-, if you want to solve for the oxidation state of Cl, you'd have the equation x + 4(-2) = -1. Here, -2 is the known oxidation number of oxygen, and since we have 4 oxygens, we multiply by 4. The -1 represents the overall charge of the ion. Solving for x, we would get the oxidation state of Cl in this ion to be +7. Hope this helps!

[Helen Ringley 2E]

What do we use the oxidation state for? Like why do we want to know the oxidation state and what kind of insight does it give us about the atom's behavior?

[Jessica Phung 1E]

There are also rules that you might want to just know. For example, when an element is alone in its normal state, like diatomic gases, their oxidation number is 0. So, if you see O2 in chemical reaction, its oxidation number is 0.

[Anthony_Rio_3K]

What do we use the oxidation state for? Like why do we want to know the oxidation state and what kind of insight does it give us about the atom's behavior?

To follow up on this what does oxidation state mean and what are the trends between an oxidation certain state and other characteristics of molecules?

[Anika Scott 3A]

I would recommend reading the textbook or looking into other sources because there are various rules that are applied in oxidation. For instance, the oxidation of an oxygen compound is typically -2, but if its a peroxide it is -1, or when it is bound to fluorine it is 1.

[Somin Lee]

Hi! To determine oxidation, you have to make an equation of the oxidation states you know already and solve for the oxidation state you don't know. For example, in ClO4-, if you want to solve for the oxidation state of Cl, you'd have the equation x + 4(-2) = -1. Here, -2 is the known oxidation number of oxygen, and since we have 4 oxygens, we multiply by 4. The -1 represents the overall charge of the ion. Solving for x, we would get the oxidation state of Cl in this ion to be +7. Hope this helps!

how do we know oxidation number of O is -2? Do we just memorize the number?

[Mrinalini Mishra 2L]

Hi! Yes, you'd just memorize this.

[Vashe Sundar 3H]

You usually have to memorize the basic rules and then work from there. For example, you should memorize that oxygen is typically -2 (except in peroxides) and F/Cl are -1. Knowing these rules, you can calculate the oxidation numbers for other atoms in the compound.
e.g. MnF3
Since F is -1 and MnF3 has a net charge of 0, Mn must have an oxidation state of +3.