# Ion

## Key Stage 4

### Meaning

An Ion is a particle that has a different number of protons to electrons.

An atom contains the same number of protons as electrons. When an atom loses or gains electrons it becomes an ion.
Ions can be positively charged or negatively charged.
If an atom gains electrons it becomes a negatively charged ion since there are more electrons than protons and electrons carry a negative charge.
If an atom loses electrons it becomes a positively charged ion since there are more protons than electrons and protons carry a positive charge.
 Atom Ion A Lithium atom has 3 protons and 3 electrons so it is neutral. A Lithium ion has 3 protons and 2 electrons so it has a positive charge. It now has a full Outer Shell. A Fluorine atom has 9 protons and 9 electrons so it is neutral. A Fluorine ion has 9 protons and 10 electrons so it is negative charge. It now has a full Outer Shell.
The number of electron in an ion can be found using the Atomic Number (which is the same as the Relative Atomic Charge of the nucleus) and subtracting the charge of the ion.
 A Lithium Ion A Fluorine Ion A Boron Ion An Oxygen Ion This ion has an Atomic Number (Z) of 3 and a Relative Atomic Charge (Q) of +1. Number of electrons = A - Q Number of electrons = 3 - 1 Number of electrons = 2 This ion has an Atomic Number (Z) of 9 and a Relative Atomic Charge (Q) of -1. Number of electrons = A - Q Number of electrons = 9 - (-1) Number of electrons = 10 This ion has an Atomic Number (Z) of 5 and a Relative Atomic Charge (Q) of +3. Number of electrons = A - Q Number of electrons = 5 - 3 Number of electrons = 2 This ion has an Atomic Number (Z) of 8 and a Relative Atomic Charge (Q) of -2. Number of electrons = A - Q Number of electrons = 8 - (-2) Number of electrons = 10

### References

#### AQA

Ions, page 112, GCSE Combined Science Trilogy; Physics, CGP, AQA
Ions, page 124, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Ions, page 50, GCSE Physics; Third Edition, Oxford University Press, AQA
Ions, pages 121-2, 148, 339, GCSE Combined Science Trilogy 1, Hodder, AQA
Ions, pages 16, 38-43, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Ions, pages 23, 29, 70-74, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
Ions, pages 28-30, GCSE Chemistry; The Revision Guide, CGP, AQA
Ions, pages 43, 44, GCSE Physics; The Revision Guide, CGP, AQA
Ions, pages 6-7, GCSE Chemistry, Hodder, AQA
Ions, pages 96, 113-115, 197, GCSE Combined Science; The Revision Guide, CGP, AQA
Ions; charge on, page 35, GCSE Chemistry, Hodder, AQA
Ions; charge on, pages 150-1, GCSE Combined Science Trilogy 1, Hodder, AQA
Ions; electrolysis, pages 102, 104-105, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Ions; periodicity, pages 40-41, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Ions; pH scale, page 99, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Ions; tests, pages 186-191, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Ions; transition elements, page 33, GCSE Chemistry; Third Edition, Oxford University Press, AQA

#### Edexcel

Ions, page 154, GCSE Physics, CGP, Edexcel
Ions, page 53, GCSE Chemistry, Pearson, Edexcel
Ions, page 95, GCSE Physics, Pearson Edexcel
Ions, pages 197, 359, GCSE Combined Science, Pearson Edexcel
Ions, pages 20, 21, GCSE Chemistry; The Revision Guide, CGP, Edexcel
Ions, pages 48-55, GCSE Chemistry, CGP, Edexcel
Ions, pages 49, 50, GCSE Physics; The Revision Guide, CGP, Edexcel
Ions, pages 83, 84, 172, 173, GCSE Combined Science; The Revision Guide, CGP, Edexcel
Ions; neutralisation, pages 208-209, GCSE Combined Science, Pearson Edexcel
Ions; neutralisation, pages 64-65, GCSE Chemistry, Pearson, Edexcel
Ions; spectator ions, page 210, GCSE Combined Science, Pearson Edexcel
Ions; spectator ions, page 66, GCSE Chemistry, Pearson, Edexcel
Ions; test for positive ions, pages 196-197, GCSE Chemistry, Pearson, Edexcel
Ions; tests for negative ions, pages 198-199, GCSE Chemistry, Pearson, Edexcel

#### OCR

Ions, pages 15, 18, 19, 35, Gateway GCSE Chemistry; The Revision Guide, CGP, OCR
Ions, pages 173, Gateway GCSE Physics, Oxford, OCR
Ions, pages 29, 56-57, Gateway GCSE Chemistry, Oxford, OCR
Ions, pages 86, 89-91, 108, 117, 196, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
Ions; detection/identification, pages 148-151, 272-273, Gateway GCSE Chemistry, Oxford, OCR
Ions; electrolysis, pages 122-127, Gateway GCSE Chemistry, Oxford, OCR
Ions; formulae, page 88, Gateway GCSE Chemistry, Oxford, OCR
Ions; halogen displacement reactions, page 136, Gateway GCSE Chemistry, Oxford, OCR
Ions; transition metals, page 141, Gateway GCSE Chemistry, Oxford, OCR