All Activities
Science

Inside the Atom

Overview

Students explore what atoms are made of, discovering the subatomic particles and why the arrangement of electrons determines an element's chemical behaviour.

Learning Objective
Students understand the structure of an atom in terms of protons, neutrons, and electrons and can use atomic number and mass number to describe a specific atom.

Resources needed

  • None — or coloured balls to model the atom

Lesson stages

0 / 7 done
  1. 1 Recap: atoms are the smallest particles of an element. But are they the smallest things of all?
  2. 2 Introduce three subatomic particles: proton (positive, in nucleus), neutron (neutral, in nucleus), electron (negative, in shells around nucleus).
  3. 3 Introduce atomic number: the number of protons — this defines the element.
  4. 4 Introduce mass number: protons + neutrons.
  5. 5 Model a hydrogen atom: 1 proton, 0 neutrons, 1 electron. Carbon: 6 protons, 6 neutrons, 6 electrons.
  6. 6 Explain electron shells: electrons occupy shells around the nucleus (2, 8, 8 filling order).
  7. 7 Ask: why are noble gases unreactive? (Full outer shell — no need to gain or lose electrons).

Tap a step to mark it as done.

Variations

  • Build models of the first 10 elements using coloured clay balls.
  • Introduce isotopes: atoms of the same element with different numbers of neutrons.
  • Connect to the periodic table: why elements in the same group have similar reactions.
More information

Teach: proton, neutron, electron, nucleus, shell, atomic number, mass number, charge. A simple diagram — circle for nucleus, rings for electron shells — is the most important visual tool.

Focus on protons, neutrons, and electrons and their location before introducing atomic number and mass number.

Can students draw a correct atomic model for the first five elements? Can they use atomic number and mass number to determine the number of protons, neutrons, and electrons in an atom?

Draw atomic diagrams in soil. Model with different coloured stones or clay balls.

Students often think electrons orbit the nucleus like planets. The shell model is a simplification — electrons exist in probability clouds, not fixed orbits.

Atomic structure explains the periodic table, chemical bonding, and the properties of elements.

Activity details
Secondary Challenging 25 minutes no prep Whole Class, Small Group Indoor & Outdoor
Topics
Atomic Structure Subatomic Particles Chemistry