| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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New experimental evidence may lead to a scientific model being changed or replaced. |
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Why might the scientific model of the atom change over time? |
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Before the discovery of the electron, atoms were thought to be tiny spheres that could not be divided. |
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What where the atoms thought to be like before the discovery of the atom? Produce a timeline to show how our ideas about atoms have changed since ancient Greek times.
Find out about the origins of the words protons, neutrons and electrons. |
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The discovery of the electron led to the plum pudding model of the atom. |
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What did the discovery of the electron lead to? |
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The plum pudding model suggested that the atom is a ball of positive charge with negative electrons embedded in it. |
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What did the plum pudding model suggest? |
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The results from the alpha particle scattering experiment led to the conclusion that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged. This nuclear model replaced the plum pudding model. |
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What did the results from the alpha particle scattering experiment lead to? Model the alpha scattering experiment using marbles and an upturned tray lifted just off the table with a hidden small mass in the centre.
Roll the marbles (alpha particles) under the tray and note down how many go straight through, how many deflected slightly and how many deflected straight back.
Use these observations to come up with a model of what is under the box (model of the atom). Mimicking Rutherford.
---OR---
by flicking a 1p coin through stack of 2p coins. The 1p coin represents the alpha particle and the stack of 2p coins the gold foil. How must the stacks be arranged in order that 90% of the coins go straight through without scattering? What conclusion can be drawn about the arrangement of atomic nuclei in a material and the amount of free space between nuclei? |
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Niels Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances. The theoretical calculations of Bohr agreed with experimental observations.
Details of experimental work supporting the Bohr model are not required. |
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How did Niel Bohr adapt the nuclear model? |
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Later experiments led to the idea that the positive charge of any nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name proton was given to these particles. |
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What did later experiments on the atom lead to? |
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The experimental work of James Chadwick provided the evidence to show the existence of neutrons within the nucleus. This was about 20 years after the nucleus became an accepted scientific idea.
Details of Chadwick?s experimental work are not required. |
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What did the experimental work of James Chadwick provide evidence of? |
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Students should be able to describe why the new evidence from the scattering experiment led to a change
in the atomic model. |
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Describe why the new evidence from the scattering experiment led to a change
in the atomic model. |
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Students should be able to describe the difference between the plum pudding model of the atom and the nuclear model of the atom. |
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What is the difference between the plum pudding model of the atom and the nuclear model of the atom. |
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