AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
This was about 20 years after the nucleus became an accepted scientific…
Full specification wording
The development of the model of the atom (common content with chemistry): This was about 20 years after the nucleus became an accepted scientific idea.
The nuclear model was established around 1911, when the alpha scattering results were explained, and Bohr adapted it soon afterwards.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 12 of 12
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
The nuclear model was established around 1911, when the alpha scattering results were explained, and Bohr adapted it soon afterwards. The evidence for the neutron did not arrive until about twenty years later. That gap is worth noticing, because it shows how a model develops: the nuclear model was not thrown away when the neutron turned up, it was completed. Each stage waited on new experimental techniques and on evidence that the existing picture could not explain. The order to remember is solid sphere, plum pudding, nuclear model, Bohr's fixed orbits, the subdivision of nuclear charge into protons, and finally the neutron, about two decades after the nucleus itself was accepted.
What earns the marks
- Placing the evidence for the neutron about twenty years after the nucleus was accepted.
- Putting the models in the order solid sphere, plum pudding, nuclear, Bohr, neutron.
- Stating that the delay shows models are refined over time as new evidence appears.
- Stating that the nuclear model was added to, not abandoned, when the neutron was found.
Common mistakes and how to put them right
Including neutrons in the original nuclear model as first proposed.
Reversing the order of the plum pudding and nuclear models.
Saying the whole nuclear model was replaced when the neutron was discovered.
Assuming every stage of the story happened within a few months of the last.
Exam tips
- Learn the sequence of models as a list; questions often just ask you to order them.
- Say the nuclear model was refined rather than replaced when the neutron was found.
- If a question asks why development took so long, point to the need for new evidence and better apparatus.
Try the lesson
The start of the The development of the model of the atom (common content with chemistry): This was about 20 years after the nucleus became an accepted scientific idea. lesson, made from checked teaching notes for this specification point.
Have a go first
James Chadwick provided evidence for the existence of the neutron. Approximately how many years after the nucleus became an accepted scientific idea did this occur?
Listen
The nuclear model was established around 1911, when the alpha scattering results were explained, and Bohr adapted it soon afterwards. The evidence for the neutron did not arrive until about twenty years later. That gap is worth noticing, because it shows how a model develops: the nuclear model was not thrown away when the neutron turned up, it was completed. Each stage waited on new experimental techniques and on evidence that the existing picture could not explain. The order to remember is solid sphere, plum pudding, nuclear model, Bohr's fixed orbits, the subdivision of nuclear charge into protons, and finally the neutron, about two decades after the nucleus itself was accepted. A strong answer earns marks for these points. placing the evidence for the neutron about twenty years after the nucleus was accepted. putting the models in the order solid sphere, plum pudding, nuclear, Bohr, neutron. stating that the delay shows models are refined over time as new evidence appears. stating that the nuclear model was added to, not abandoned, when the neutron was found. Exam tip: Learn the sequence of models as a list; questions often just ask you to order them.
See it
Put it in order
Put these steps in the order they happen.
- 1. Nuclear model refined, not replaced
- 2. Neutron, about twenty years after the nucleus was accepted
- 3. Nuclear model
- 4. Nuclear charge subdivided into protons
- 5. Solid sphere
- 6. Plum pudding
- 7. Bohr's fixed orbits
Key words
Say what each word means before you turn the card.
timeline of models
Try answering aloud or in your head before turning the card.
refining a model
Try answering aloud or in your head before turning the card.
twenty year gap
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how science develops
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See every definition
- timeline of models
- The order to remember is solid sphere, plum pudding, nuclear model, Bohr's fixed orbits, the subdivision of nuclear charge into protons, and finally the neutron.
- refining a model
- The nuclear model was not thrown away when the neutron turned up, it was completed.
- twenty year gap
- The evidence for the neutron did not arrive until about twenty years after the nucleus became an accepted scientific idea.
- how science develops
- Each stage waited on new experimental techniques and on evidence that the existing picture could not explain.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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