Specification Point 1.37:
Understand how ions are formed by electron loss or gain

How Ions are Formed

An ion is an electrically charged atom or a group of atoms that are formed by the loss or gain of electrons.

  • This loss or gain of electrons leave a full outer shell of electrons.
  • The electronic structure of an ion will be the same as that of a noble gas – such as Helium, Neon and Argon.

Ionisation of metals and non-metals:

  • Metals: They will lose electrons to another atom and become positively charged ions
  • Non-metals: They will gain electrons from another atom to become negatively charged ions

Metals

Positive sodium and aluminium ions, CIE IGCSE Chemistry

Positively charged sodium and aluminium ions

Non-metals

Negative oxide and chloride ions, CIE IGCSE Chemistry

Negatively charged oxide and chloride ions

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.