Oxidation numbers notes

What is an oxidation number?

An oxidation number indicates the degree of oxidation of an atom in a compound. It reflects the number of electrons lost, gained, or shared.

Oxidation number of oxygen?

Typically -2 in compounds. Exceptions include peroxides, where it is -1.

True or false: Oxidation states can be fractional.

False, because oxidation states are always whole numbers.

What is the oxidation number of hydrogen?

Generally +1 when bonded to nonmetals, and -1 when bonded to metals.

Difference between oxidation and reduction.

- Oxidation: loss of electrons - Reduction: gain of electrons

Fill in the blank: In a neutral compound, the sum of oxidation numbers equals _____.

Zero.

What is the oxidation number of alkali metals?

Always +1 in compounds.

True or false: Oxidation numbers can be negative.

True, because many elements can have negative oxidation states.

What does a higher oxidation number indicate?

It indicates a greater loss of electrons and a higher degree of oxidation.

How do you determine oxidation states in polyatomic ions?

The sum of the oxidation states must equal the ion's charge.

Question: What oxidation number does carbon typically have in organic compounds?

Varies, commonly +4 or -4.

Oxidation number of halogens in compounds?

Usually -1, unless bonded to oxygen or other halogens.

Which oxidation number is not allowed?

Oxidation numbers greater than the group number for main group elements.

What is the oxidation state of sulfur in SO$\displaystyle _2$?

+4.

Fill in the blank: The oxidation number of a free element is _____.

Zero.

True or false: Transition metals always have a fixed oxidation state.

False, because transition metals can exhibit multiple oxidation states.

What is the oxidation number of nitrogen in NH$\displaystyle _3$?

-3.