Model of the atom showing that negative electrons are embedded in a ball of positive charge.

A stream of positive alpha particles fired through a thin piece of gold foil. This lead to an update of the atomic model, from the plum pudding model to nuclear model.

Model of the atom with a small positive charge in the centre surrounded by a cloud of orbiting electrons. The atom is mostly empty space. This model is sometimes called the planetary model.

Developing a model for atoms (Geiger and Marsden)

Chemistry

In the Structure and Bonding unit, pupils will build on their understanding of atomic structure to explore different types of chemical bonding and how these bonds affect the properties of substances.

In the Atoms, Elements and Compounds unit, pupils learned about the differences between atoms, elements, and compounds, as well as their chemical symbols and formulae.

Atomic structure and the periodic table

Which scientist is credited with the plum pudding model of the atom?

Place the following atomic models in the order they were proposed, starting with the model first proposed:

Electrons orbit the nucleus in fixed paths.

The atom is mostly empty space with a dense centre.

Negative electrons are scattered throughout a positive sphere.

What does the nuclear model of the atom suggest?

True or False? Chadwick’s contribution to the atomic model was the discovery of the neutron.

Which of the following experiments disproved the plum pudding model?

Atom is a ball of positive charge with embedded electrons.

Dense nucleus surrounded by orbiting electrons (like planets + sun).

Match the description to the correct atomic model term.

What are the three main subatomic particles found in an atom?

Which of the following particles is negatively charged?

True or false? Protons and electrons have equal but opposite charges. 

{{}}, along with protons, make up the nucleus of an atom. They add to the mass of an atom but do not carry a charge.

According to the principles of electricity and magnetism, what happens when two electrons come close to each other?

True or false? Neutrons have a greater mass than protons.

This lesson will be removed by end of Summer Term 2025.

Developing a model for atoms (Geiger and Marsden)

Lesson outcome

This lesson will be removed by end of Summer Term 2025.