#23
4.1.1.5 Size and mass of atoms
Paper 1 · Higher combined
Spec reference: 4.1.1.5 (under 4.1.1).
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 number.
KO match: Atomic Number and Mass Number
Support videos
- FreeScienceLessons (topic playlist): (use links below)
- FreeScienceLessons (Atomic structure playlist): https://www.youtube.com/playlist?list=PL9IouNCPbCxULWXCO9jt0PsuAbxYpw2_1
Self-assessment (checklist)
- I can use the nuclear model to describe atoms.
- I can state the radius of an atom.
- I can describe how the radius of a nucleus compares to
- I can state the relative mass of a proton.
- I can state the relative mass of a neutron.
- I can state the relative mass of an electron.
- I can describe how the number of protons and neutrons
Key steps (method)
- Identify what the question is testing and use precise chemistry vocabulary.
- If it’s a calculation: write the equation/formula first, then substitute carefully.
Common mistakes
- Missing units/state symbols when asked.
- Giving a statement without linking cause → effect.
Exam-style questions (quick)
- Define the key term(s) for this point in the spec.
- Explain a typical property/result using particle/bonding ideas.
- Do a short calculation or interpretation step relevant to this point.
Practice questions
- PMT: Atomic structure (questions + notes): https://www.physicsandmathstutor.com/chemistry-revision/gcse-aqa/atomic-structure-and-periodic-table