Pickles AcademyStart for free

Structure of the atom – practice for Years 8–9

Sample questions on Structure of the atom with the right answer and a worked solution, from easy to hard. In the Pickles Academy app a child gets new questions of the same kind every time, so they can't just learn the answers by heart.

Subject
Chemistry
Year
Years 8–9
Curriculum area
Atoms and elements

Question types: Protons, neutrons and electrons

Rule: Structure of the atom

The nucleus is made of protons (+) and neutrons (no charge); electrons (−) are around it.

Atomic number = number of protons = number of electrons in an atom. Mass number = protons + neutrons.

Example: Al: atomic number 13, mass number 27 → 13 protons, 13 electrons, 27 − 13 = 14 neutrons

Watch out: The mass number is not the number of neutrons: take the atomic number away from it.

Sample questions

  1. Question 1 Easy

    What is the mass number A of the atom in the picture?

    8 p⁺8 n⁰
    Show the solution
    Answer: 16

    How it works: A = 8 + 8 = 16.

  2. Question 2 Normal

    An atom of oxygen (O) has atomic number 8 and mass number 16. How many neutrons does it have?

    Show the solution
    Answer: 8

    How it works: n = A − Z = 16 − 8 = 8.

  3. Question 3 Hard

    How many electrons does the ion Ca²⁺ have? The atomic number of calcium is 20.

    Show the solution
    Answer: 18

    How it works: A positive ion has lost electrons: 20 − 2 = 18.

Related topics

All Chemistry topics

Keep practising in the app

In a minute, your child has their own avatar and a first task. Free, no ads, data in the EU.

Start for free