This topic summary covers Topic Summary: Atomic Structure within Atomic Structure for GCSE Physics. Revise Atomic Structure in Atomic Structure for GCSE Physics with 13 exam-style questions and 25 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 12 of 12 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 12 of 12
Practice
13 questions
Recall
25 flashcards
Topic Summary: Atomic Structure
Key Terms
- Atomic number (Z): Number of protons
- Mass number (A): Protons + neutrons
- Isotope: Same element, different neutron number
- Nucleon: Proton or neutron in nucleus
- Ion: Atom with gained or lost electrons
Key Facts
- Proton: charge +1, mass 1
- Neutron: charge 0, mass 1
- Electron: charge −1, mass ~0
- Neutral atom: protons = electrons
- Nucleus: 1/10,000 of atom diameter
- Atom is 99.9999999999999% empty space
Key Equation
- Neutrons = A − Z
- Example: ²³₁₁Na → 23 − 11 = 12 neutrons
Exam Tips
- Z = bottom number = protons
- A = top number = protons + neutrons
- Isotopes: same Z, different A
- Same chemical properties, different mass
Quick Check: Two atoms both have 8 protons. One has 8 neutrons, the other has 10. Are they isotopes? Explain your answer.
Yes, they are isotopes. They have the same number of protons (same element — oxygen), but different numbers of neutrons (mass numbers 16 and 18). These are oxygen-16 and oxygen-18.