Describe the experimental setup used in the alpha-particle scattering experiment.

Alpha particles were fired at a thin gold foil, and their deflections were observed using a detector that could be moved around the foil to different positions.

What evidence does large-angle scattering of alpha particles provide about atomic structure?

It provides evidence that the positive charge and most of the mass of an atom is concentrated in a small central nucleus.

Describe the simple nuclear model of the atom.

The atom consists of a central nucleus containing protons and neutrons, surrounded by orbiting electrons.

OCR A-Level Physics A H556

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Nuclear and Particle Physics

Alpha-particle scattering and the nuclear model

3 things to know
Papers 1, 2 and 3

Overview

Recall questions on the alpha-particle scattering experiment and what it showed, the simple nuclear model, and the orders of magnitude of atomic and nuclear radii.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What was observed for most alpha particles in the gold foil scattering experiment, and what does this indicate about atomic structure?

Key term

What happened to a small fraction of alpha particles in the scattering experiment?

Key term

Why does the deflection of alpha particles indicate that the nucleus is positively charged?

Questions from this subtopic

Each one with the model answer underneath.

1
Describe the experimental setup used in the alpha-particle scattering experiment.
Model answer
Alpha particles were fired at a thin gold foil, and their deflections were observed using a detector that could be moved around the foil to different positions.
2
What was observed for most alpha particles in the gold foil scattering experiment, and what does this indicate about atomic structure?
Model answer
Most alpha particles passed straight through with little or no deflection, indicating that atoms are mostly empty space.
3
What happened to a small fraction of alpha particles in the scattering experiment?
Model answer
A small fraction were deflected through large angles, and very few were scattered back towards the source.
4
What evidence does large-angle scattering of alpha particles provide about atomic structure?
Model answer
It provides evidence that the positive charge and most of the mass of an atom is concentrated in a small central nucleus.
5
Why does the deflection of alpha particles indicate that the nucleus is positively charged?
Model answer
The nucleus must be positively charged because it repels the positively charged alpha particles, causing them to deflect.
6
Describe the simple nuclear model of the atom.
Model answer
The atom consists of a central nucleus containing protons and neutrons, surrounded by orbiting electrons.

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