AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Relative electrical charges of subatomic particles: The relative electrical charges of the particles in atoms are:
Atoms contain three subatomic particles whose electrical charges are compared using relative values rather than coulombs.
- 2 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Atoms contain three subatomic particles whose electrical charges are compared using relative values rather than coulombs. A proton carries a relative charge of 1⁺, an electron carries a relative charge of 1⁻, and a neutron carries no charge, written as 0. These values are relative because they compare each particle's charge with the magnitude of a proton's charge, so the numbers stay simple. For example, a nucleus containing 11 protons has a total positive charge of 11⁺, while 11 electrons surrounding it give a total negative charge of 11⁻. Because the charges are equal in magnitude and opposite in sign, they cancel. Knowing these relative charges lets you work out the overall charge of any atom or ion from its particle counts, and it underpins later work on ionic bonding and electrolysis.
What earns the marks
- State that a proton has a relative electrical charge of 1⁺.
- State that an electron has a relative electrical charge of 1⁻.
- State that a neutron has a relative electrical charge of 0, meaning it is neutral.
- Explain that the values are relative to the magnitude of the charge on a proton, so they are not measured in coulombs.
- Use the relative charges to calculate the overall charge of a particle from its numbers of protons and electrons, for example 12 protons and 10 electrons gives an overall charge of 2⁺.
Common mistakes and how to put them right
Writing the neutron's charge as 1⁰ or leaving it blank.
Put it right: The correct value is 0, because a neutron is electrically neutral.
Giving the electron a positive charge.
Put it right: The electron is negative, so its relative charge is 1⁻, while the proton is 1⁺.
Treating the relative charge values as coulomb measurements.
Put it right: They are comparisons with the proton's charge magnitude, so no unit is attached.
Exam tips
- Learn the three values as a matched set: proton 1⁺, neutron 0, electron 1⁻.
- When a question gives particle numbers, subtract the number of electrons from the number of protons to find the overall charge.
- Check the sign as well as the size of any charge you write, because a missing or reversed sign loses the mark even when the number is right.
Try the lesson
The start of the Relative electrical charges of subatomic particles: The relative electrical charges of the particles in atoms are: lesson, made from checked teaching notes for this specification point.
Have a go first
In an atom, which subatomic particle has a relative electrical charge of 1⁻?
Listen
Atoms contain three subatomic particles whose electrical charges are compared using relative values rather than coulombs. A proton carries a relative charge of 1⁺, an electron carries a relative charge of 1⁻, and a neutron carries no charge, written as 0. These values are relative because they compare each particle's charge with the magnitude of a proton's charge, so the numbers stay simple. For example, a nucleus containing 11 protons has a total positive charge of 11⁺, while 11 electrons surrounding it give a total negative charge of 11⁻. Because the charges are equal in magnitude and opposite in sign, they cancel. Knowing these relative charges lets you work out the overall charge of any atom or ion from its particle counts, and it underpins later work on ionic bonding and electrolysis. A strong answer earns marks for these points. State that a proton has a relative electrical charge of 1⁺. State that an electron has a relative electrical charge of 1⁻. State that a neutron has a relative electrical charge of 0, meaning it is neutral. Explain that the values are relative to the magnitude of the charge on a proton, so they are not measured in coulombs. Exam tip: Learn the three values as a matched set: proton 1⁺, neutron 0, electron 1⁻.
See it
Key words
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Subatomic particle properties
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Link between particle counts and overall charge
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See every definition
- Subatomic particle properties
- Atoms contain three subatomic particles whose electrical charges are compared using relative values rather than coulombs.
- Link between particle counts and overall charge
- Knowing these relative charges lets you work out the overall charge of any atom or ion from its particle counts.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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