The atomic model has changed over time.
Dalton, Thomson, Rutherford (Geiger and Marsden), Bohr and Chadwick have all suggested atomic models.
The plum pudding model of the atom & the nuclear model are two important models in the history of the atom's discovery.
New evidence from the scattering experiment led to a change in the atomic model.

Keywords

Plum pudding model - Model of the atom showing that negative electrons are embedded in a ball of positive charge.
Rutherford's experiment - 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.
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.

Common misconception

Confusion between the models and the order in which they were conceived. Also, pupils often mix up which subatomic particles are present in each model.

Practise is required listing the key features of each model and the subatomic particles present. A timeline with the key features present helps pupils to understand the process of discovery and how long this can take.

The drawing of a time-line and fact-files of each model help pupils to organise the information.

Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.

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

Correct answer: Protons

Correct answer: Neutrons

Correct answer: Electrons

Atoms

Molecules

Q2.

Which of the following particles is negatively charged?

Proton

Atom

Correct answer: Electron

Nucleus

Neutron

Q3.

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

Correct answer: True

False

Q4.

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

Correct Answer: neutrons

Q5.

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

They attract each other.

They combine to form a neutron.

Correct answer: They repel each other.

They remain neutral and unaffected.

Q6.

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

True

Correct answer: False

Exit quiz

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6 Questions

Q1.

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

Dalton

Correct answer: Thomson

Rutherford

Bohr

Q2.

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

1 - Dalton’s atomic model

2 - Plum pudding model

3 - Rutherford's nuclear model

4 - Bohr’s model

Q3.

What does the nuclear model of the atom suggest?

The atom is a solid sphere.

Electrons orbit the nucleus in fixed paths.

Correct answer: The atom is mostly empty space with a dense centre.

Negative electrons are scattered throughout a positive sphere.

Q4.

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

Correct answer: True

False

Q5.

Which of the following experiments disproved the plum pudding model?

Cathode ray tube experiment

Correct answer: Gold foil experiment

Oil drop experiment

Photoelectric effect

Q6.

Match the description to the correct atomic model term.

Correct Answer:Bohr’s model,Electrons orbit in fixed paths.

Electrons orbit in fixed paths.

Correct Answer:Plum pudding model,Atom is a ball of positive charge with embedded electrons.

Atom is a ball of positive charge with embedded electrons.

Correct Answer:Nuclear model,Dense nucleus surrounded by orbiting electrons (like planets + sun).

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

Correct Answer:Dalton’s model,Atoms are indivisible.

Atoms are indivisible.