Explain why atoms have no overall electrical charge, even though they contain charged particles.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Atoms are made up of protons, neutrons, and electrons. Despite containing particles that carry electrical charges, atoms themselves are electrically neutral.
Model answer (4 marks)
Protons carry a positive charge and electrons carry a negative charge (neutrons are neutral). In a neutral atom the number of protons equals the number of electrons. The positive charge from the protons is therefore equal in magnitude to the negative charge from the electrons, so the net charge is zero.
Examiner tips
- Use the term ‘net charge’ and mention neutrons are neutral
- Show the equality of protons and electrons explicitly
- Explain that equal magnitude opposite charges cancel
Common mistakes
- Confusing the charge of neutrons with that of protons
- Failing to state that the numbers of protons and electrons are equal
- Using vague language such as ‘they cancel out’ without showing the charge balance
Mark scheme (4 marks)
- Protons carry a positive charge and electrons carry a negative charge (neutrons have no charge / are neutral)
- The number of protons equals the number of electrons in an atom
- The positive charges (from protons) and negative charges (from electrons) are equal in magnitude
- Therefore the overall / net charge is zero
Key terms in this question
Related
- All Eduqas GCSE Chemistry revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Atomic structure and the periodic table questions
- Explain how the atomic number and mass number of an atom can be used to determin…
- Describe how scientists' understanding of atomic structure changed with the deve…
- Isotopes of an element have the same chemical properties but different physical …
- Elements in the periodic table are arranged in periods and groups. Explain what …