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Edexcel IGCSE Chemistry · Spec 1.14-1.17

Atomic Structure & Isotopes

The structure of the atom, atomic number and mass number, and isotopes.

Chemistry revision video

Atomic Structure & Isotopes

Spec 1.14-1.17

What you need to know

  • Describe the particles that make up an atom
  • Use atomic number and mass number
  • Explain what isotopes are, and work out a relative atomic mass

Active recall

Quick check

Answer each question before opening the answer.

State the relative charge and relative mass of a proton, neutron and electron.

Proton: charge +1, mass 1. Neutron: charge 0, mass 1. Electron: charge −1, mass negligible (~1/1836).

What are isotopes?

Atoms of the same element (same number of protons) with different numbers of neutrons.

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