Fundamental particles
Cambridge A-Level Physics (9702) · Unit 11: Particle physics · 8 flashcards
Fundamental particles is topic 11.2 in the Cambridge A-Level Physics (9702) syllabus , positioned in Unit 11 — Particle physics , alongside Atoms, nuclei and radiation. In one line: The six flavours of quarks are: up, down, strange, charm, top, and bottom. These are fundamental particles.
Marked as AS Level: examined at AS Level in Paper 1 (Multiple Choice), Paper 2 (AS Structured Questions) and Paper 3 (Advanced Practical Skills). The same content may also be assumed in Paper 4 (A Level Structured Questions).
The deck below contains 8 flashcards — 4 definitions and 4 key concepts — covering the precise wording mark schemes reward. Use the 4 definition cards to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
The six flavours (types) of quarks
The six flavours of quarks are: up, down, strange, charm, top, and bottom. These are fundamental particles.
What the Cambridge 9702 syllabus says
2025-2027 syllabus, in our words · AS LevelWhat the syllabus expects you to be able to do in this topic, in plain English. For the exact wording, see the official syllabus (PDF).
- Understand that quarks are fundamental particles with six flavours (types): up, down, charm, strange, top and bottom.
- Recall and use the charge carried by each quark flavour, and understand that the matching antiquark carries the opposite charge (no other quark properties need to be known).
- Recall that neither protons nor neutrons are fundamental particles, and describe the quark composition of each.
- Understand that hadrons are either baryons (made of three quarks) or mesons (made of a quark and an antiquark).
- Describe how the quark composition changes in β⁻ decay and in β⁺ decay.
- Recall that leptons are fundamental particles, and that electrons and neutrinos belong to this group.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9702 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Tips to avoid common mistakes in Fundamental particles
- › State that neutrons are not fundamental as they are composed of quarks (up, down, down).
- › In β⁻ decay, state that a down quark changes to an up quark (d to u) to describe the change in the nucleon's quark composition.
- › Identify the specific change (e.g., an up quark changes to a down quark) rather than just stating the starting and ending compositions.
- › When asked for the origin of a particle in decay, describe the specific quark or nucleon change occurring.
What are the six flavours (types) of quarks?
The six flavours of quarks are: up, down, strange, charm, top, and bottom. These are fundamental particles.
What is the charge of an up quark, and what is the charge of its corresponding antiquark?
An up quark has a charge of +2/3 e. An anti-up quark has a charge of -2/3 e.
Describe the quark composition of a proton and a neutron.
A proton consists of two up quarks and one down quark (uud). A neutron consists of one up quark and two down quarks (udd).
What distinguishes a baryon from a meson in terms of quark composition?
A baryon is a hadron consisting of three quarks (qqq). A meson is a hadron consisting of one quark and one antiquark (q anti-q).
Describe the change in quark composition during β- decay.
During β- decay, a neutron (udd) converts into a proton (uud). One down quark changes into an up quark, emitting an electron and an antineutrino: d → u + e- + anti-νe.
Describe the change in quark composition during β+ decay.
During β+ decay, a proton (uud) converts into a neutron (udd). One up quark changes into a down quark, emitting a positron and a neutrino: u → d + e+ + νe.
Name two fundamental particles that are classified as leptons.
Electrons and neutrinos are examples of fundamental particles called leptons. They are not composed of quarks.
Are protons and neutrons fundamental particles? Explain why or why not.
Protons and neutrons are *not* fundamental particles. They are composite particles made of quarks (protons = uud, neutrons = udd). Fundamental particles are not made of smaller constituents.
Review the material
Read full revision notes on Fundamental particles — definitions, equations, common mistakes, and exam tips.
Read NotesMore topics in Unit 11 — Particle physics
Fundamental particles sits alongside these A-Level Physics decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Key terms covered in this Fundamental particles deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
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