Oxidation States and Half Reactions

Front

What is an oxidation state?

Back

An oxidation state (or oxidation number) is a measure of the degree of oxidation of an atom in a chemical compound, indicating the number of electrons lost or gained.

Front

What does reduction mean in terms of electron transfer?

Back

Reduction is the gain of electrons by an atom or ion.

Front

What does oxidation mean in terms of electron transfer?

Back

Oxidation is the loss of electrons by an atom or ion.

Front

Identify the oxidizing agent in a redox reaction.

Back

The oxidizing agent is the substance that gains electrons and is reduced in the reaction.

Front

Identify the reducing agent in a redox reaction.

Back

The reducing agent is the substance that loses electrons and is oxidized in the reaction.

Front

What is a half-reaction?

Back

A half-reaction is an equation that shows either the oxidation or reduction process separately in a redox reaction.

Front

How do you determine the oxidation state of an element in a compound?

Back

The oxidation state can be determined using rules such as the oxidation state of free elements is zero, the oxidation state of monoatomic ions is equal to their charge, and in compounds, the sum of oxidation states must equal the overall charge.

Front

What is the oxidation state of oxygen in most compounds?

Back

The oxidation state of oxygen is usually -2, except in peroxides where it is -1.

Front

What is the oxidation state of hydrogen in most compounds?

Back

The oxidation state of hydrogen is usually +1, except when bonded to metals in binary metal hydrides where it is -1.

Front

What happens to the oxidation state of an element that is oxidized?

Back

The oxidation state of an oxidized element increases.