GCSE Chemistry (AQA) chapter 1: Atomic structure and the periodic table MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

39 exam-style questions on Atomic structure and the periodic table, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

39 questions · 4 topics · 10 per test

Test this chapter freeAll GCSE Chemistry (AQA) chapters

What chapter 1 covers

Ten Atomic structure and the periodic table questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. Why are the noble gases unreactive?

  1. A
    they are gases, and gases cannot take part in reactions
  2. B
    their atoms have only one electron in the outer shell
  3. C
    their atoms already have full outer shells of electrons
  4. D
    their atoms are joined in molecules by strong covalent bonds
Show answer

Answer: C. A full outer shell is a stable arrangement, so noble gas atoms do not easily gain, lose or share electrons. They exist as single atoms.

2. How many protons, neutrons and electrons are in the ion 27Al3+? (atomic number of aluminium = 13)

  1. A
    13 protons, 14 neutrons, 13 electrons
  2. B
    13 protons, 27 neutrons, 10 electrons
  3. C
    13 protons, 14 neutrons, 10 electrons
  4. D
    14 protons, 13 neutrons, 10 electrons
Show answer

Answer: C. Neutrons = 27 − 13 = 14. The 3+ charge means 3 electrons have been lost, so 13 − 3 = 10 electrons.

3. Which statement about the isotopes carbon-12 and carbon-14 is correct?

  1. A
    they react differently because they have different numbers of neutrons
  2. B
    they have the same mass number because both are carbon
  3. C
    they react in the same way because their electronic structures are identical
  4. D
    they have different atomic numbers because their nuclei have different masses
Show answer

Answer: C. Isotopes have the same number of protons and electrons but different numbers of neutrons. Chemistry depends on electrons, so they react the same way.

4. Solid calcium carbonate reacts with hydrochloric acid. Which equation has correct state symbols and is balanced?

  1. A
    CaCO3(s) + 2HCl(l) → CaCl2(aq) + H2O(g) + CO2(g)
  2. B
    CaCO3(aq) + 2HCl(aq) → CaCl2(s) + H2O(l) + CO2(g)
  3. C
    CaCO3(s) + HCl(aq) → CaCl2(aq) + H2O(l) + CO2(aq)
  4. D
    CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)
Show answer

Answer: D. Calcium carbonate is a solid; hydrochloric acid and calcium chloride are dissolved (aq); water is liquid and carbon dioxide is a gas. Two HCl are needed to balance the two Cl in CaCl2.

5. Which technique is used to obtain pure water from salt solution?

  1. A
    simple distillation
  2. B
    paper chromatography with water as solvent
  3. C
    filtration through fine filter paper
  4. D
    crystallisation by slow cooling
Show answer

Answer: A. Distillation boils off the water and condenses it, leaving the salt behind. Filtration cannot remove a dissolved solid.

6. What is the electronic structure of a calcium atom (atomic number 20)?

  1. A
    2,18
  2. B
    2,8,8,2
  3. C
    2,8,10
  4. D
    2,8,2,8
Show answer

Answer: B. At GCSE the shells fill 2, 8, 8, then the fourth shell: 2 + 8 + 8 + 2 = 20. The third shell holds only 8 before the fourth starts.

7. The boiling points of neon, argon and krypton are −246 °C, −186 °C and −153 °C. Which is the best estimate for the boiling point of xenon, the next noble gas in the group?

  1. A
    about −260 °C
  2. B
    about −190 °C
  3. C
    about −153 °C
  4. D
    about −110 °C
Show answer

Answer: D. Boiling points rise down Group 0 as the atoms get larger and the relative atomic mass increases, so xenon must be higher than −153 °C. It is about −108 °C.

8. Why did Mendeleev leave gaps in his periodic table?

  1. A
    he left space for elements he predicted would be discovered later
  2. B
    he had no room for the transition metals on the page he used
  3. C
    he left space for the noble gases, which he knew were unreactive
  4. D
    he found some elements were too unstable to place in a group
Show answer

Answer: A. Mendeleev left gaps so that elements with similar properties lined up in groups, and predicted properties of undiscovered elements such as germanium. The noble gases had not been discovered.

9. Which ion has the electronic structure 2,8?

  1. A
    K+
  2. B
    Li+
  3. C
    Cl−
  4. D
    Na+
Show answer

Answer: D. Sodium (2,8,1) loses one electron to become 2,8. Cl− and K+ are both 2,8,8; Li+ is 2.

10. The radius of a nucleus is about 1 × 10−14 m and the radius of an atom is about 1 × 10−10 m. How many times larger is the radius of the atom than that of its nucleus?

  1. A
    1 000 000 times
  2. B
    10 000 times
  3. C
    1000 times
  4. D
    100 times
Show answer

Answer: B. 10−10 ÷ 10−14 = 104, so the atom's radius is about 10 000 times that of the nucleus. This is why most of an atom is empty space.

Start the chapter testAbout the GCSE Chemistry (AQA) test

Read the notes for this chapter

Ways to practise this chapter

Atomic structure and the periodic table: questions students ask

How many Atomic structure and the periodic table MCQs are there?

39, each with the answer and a short explanation, across 4 topics: 4.1.1 Atoms, elements, compounds and mixtures, 4.1.1 Atomic models, subatomic particles, isotopes and electronic structure, 4.1.2 The periodic table: development, Group 0, Group 1 and Group 7, 4.1.3 Properties of transition metals. Every chapter test draws ten of them, so you can take it many times.

Is the GCSE Chemistry (AQA) chapter 1 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

Keep going

Chapter 2: Bonding, structure, and the properties of matter →All chaptersStuck? Ask a question