Starter quiz
- What are the three main subatomic particles found in an atom?
- Protons ✓
- Neutrons ✓
- Electrons ✓
- Atoms
- Molecules
-
- Which of the following particles is negatively charged?
- Proton
- Atom
- Electron ✓
- Nucleus
- Neutron
-
- True or false? Protons and electrons have equal but opposite charges.
- True ✓
- False
- ______, along with protons, make up the nucleus of an atom. They add to the mass of an atom but do not carry a charge.
- 'neutrons' ✓
- 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.
- They repel each other. ✓
- They remain neutral and unaffected.
-
- True or false? Neutrons have a greater mass than protons.
- True
- False ✓
Exit quiz
- Which scientist is credited with the plum pudding model of the atom?
- Dalton
- Thomson ✓
- Rutherford
- Bohr
-
- 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
- What does the nuclear model of the atom suggest?
- The atom is a solid sphere.
- 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.
-
- True or False? Chadwick’s contribution to the atomic model was the discovery of the neutron.
- True ✓
- False
- Which of the following experiments disproved the plum pudding model?
- Cathode ray tube experiment
- Gold foil experiment ✓
- Oil drop experiment
- Photoelectric effect
-
- Match the description to the correct atomic model term.
- Bohr’s model⇔Electrons orbit in fixed paths. ✓
- Plum pudding model⇔Atom is a ball of positive charge with embedded electrons. ✓
- Nuclear model⇔Dense nucleus surrounded by orbiting electrons (like planets + sun). ✓
- Dalton’s model⇔Atoms are indivisible. ✓
Worksheet
Presentation
Video
Lesson Details
Key learning points
- 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.
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.
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.