Oxidation, Reduction and Redox Equations

Oxidation in terms of oxygen

Addition of oxygen

Reduction in terms of oxygen

Removal of oxygen

Oxidation in terms of hydrogen

Oxidation is the removal of hydrogen

Reduction in terms of hydrogen

Addition of hydrogen

Oxidation in terms of electrons

Oxidation in the loss of electrons

Reduction in terms of electrons

Reduction is the gain of electrons

What is an oxidising agent?

Species that oxidises another species by removing one or more electrons. When it reacts, it gains electrons and is reduced.

What is a reducing agent?

Species that reduces another species by adding one or more electrons. When it reacts, it loses electrons and is therefore oxidised.

What is a disproportionation reaction?

Simultaneous oxidation and reduction of an element in a single reaction.

What is an oxidation number?

A number assigned to an atom in a compound that represents the number of electrons lost or gained by that atom

Oxidation number of an uncombined element

0

Sum of all oxidation numbers in a neutral compound

0

Sum of all oxidation numbers of an ion

Equal to the charge on the ion

Which element in a substance is given a negative oxidation number?

The more electronegative element

When is hydrogen’s oxidation number -1?

When it’s combined with a less electronegative element

When is oxygen’s oxidation number -1?

In peroxides

Hydrogen oxidation number

+1/-1

Oxygen oxidation number

-2/-1

Group 1 metals oxidation number

+1

Group 2 metals oxidation number

+2

Aluminium oxidation number

+3

Group 7 oxidation number

-1

When do the halogens (Cl,Br,I) have an oxidation number different to -1?

In compounds with oxygen and fluorine