AQA GCSE Physics

Revision Notes

4.1.5 Positive Ions

Positive Ions

  • Electrons in the outer energy level can be knocked out from an atom
  • This can happen in a number of ways:
    • When objects are rubbed together, electrons can be removed by friction
    • When electrons absorb electromagnetic radiation they can gain enough energy to leave the atom
    • From chemical reactions
  • When one or more electrons are removed from an atom, it becomes positively charged
    • This is because an electron is negatively charged
  • The atom becomes a positive ion
    • An ion is an atom or particle with a non-zero charge

ionising-the-atom, IGCSE & GCSE Physics revision notes

When radiation passes close to atoms it can knock electrons out, leaving the atom with an overall positive charge

  • Ions are more chemically reactive than atoms because of their positive charge

Exam Tip

Definitions are very important for picking up marks on this topic. Be clear with your definitions such as ions and isotopes, and remember that ions have different numbers of electrons, whereas isotopes have different numbers of neutrons.

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