4.4.1.2 Isotopes

Spec reference: 4.4.1 (subtopic).

What you need to know

• Isotopes
• An isotope is an element with the same
• number of protons but a different number
• of neutrons. They have the same atomic
• number, but different mass numbers.
• Some isotopes are unstable and, as a result,
• decay and give out radiation. Ionising
• radiation is radiation that can knock

Self-assessment (checklist)

• I can describe how the number of electrons in an atom
• I can explain why atoms have no overall electrical
• I can describe how the number of protons in an atom
• I can describe how the number of protons and
• I can give a definition for the term ‘isotope’.
• I can explain how atoms turn into positive ions.
• I can identify the difference between isotopes given

Key steps (method)

• Identify what the question is testing and use the correct equation/definition.
• Show substitutions and units clearly.

Common mistakes

• Unit conversions, rearranging errors, or quoting a law without applying it.