3.1.7 Oxidation, reduction and redox equations - Chemistry Alevel

How do you view redox?

As electron transfer or change in oxidation state.

Oxidation state - order

sign - number

Charge - order

number - sign

Oxidation number - uncombined elements

0

Oxidation number - simple ions (one element)

Charge on ion

Oxidation number - neutral compound

Sum of oxidation numbers of all atoms in compound = 0

Oxidation number - complex ions (more than one element)

Sum of oxidation numbers of all atoms in the ion = charge on ion.

Oxidation number in compound - Hydrogen

+ 1

Oxidation number in compound - Oxygen

- 2

Oxidation number in compound - Fluorine

- 1

Oxidation number in compound - metals

Positive and usually the same as the group number.

Oxidation number in compound - non-metals

Negative with values up to their group number.

Oxidation number in compound exceptions - Hydrogen

- 1 when bonded to a metal as a hydride (e.g. NaH)

Oxidation number in compound exceptions - Oxygen

- 1 when present as a peroxide (e.g. H₂O₂)

Oxidation number in compound exceptions - Metals

Transition metals are positive but can have varying oxidation numbers.

Oxidation number in compound exceptions - Non-metals

Halogens are - 1 in ionic compounds but all except for F can be positive if covalently bonded.

Naming compounds - Roman numerals

The Roman numeral comes after the element whose oxidation number it describes.

Ingeneral reducing agents are...

Metals as they form +ve ions.

Ingeneral oxidising agents are...

Non-metals as they form -ve ions.

What can undergo reduction or oxidation?

Individual elements within a reactant.

What can be an oxidation agent or reducing agent?

A reactant (the compound).