How is a Rutherford scattering experiment carried out?
A beam of positively charged alpha particles is directed at a thin metal foil, and the directions of the scattered particles are detected.
AQA A-level Physics (7408) · 3.8.1.1
Revise AQA A-level Physics (7408) specification point 3.8.1.1, Rutherford scattering (A-level only), with free active-recall flashcards. Flip through the set or review every question and answer below.
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How is a Rutherford scattering experiment carried out?
A beam of positively charged alpha particles is directed at a thin metal foil, and the directions of the scattered particles are detected.
What are the three observed outcomes for alpha particles in Rutherford scattering?
Most pass through with little or no deflection; some are deflected through larger angles; a very small proportion are scattered backwards.
What does the passage of most alpha particles through the foil with little deflection suggest about atoms?
Atoms are mostly empty space.
What did Rutherford scattering reveal about the distribution of mass and positive charge in an atom?
Almost all the mass and positive charge are concentrated in a very small nucleus.
What causes alpha particles to be deflected in Rutherford scattering?
Electrostatic repulsion between the positively charged alpha particle and the positively charged nucleus.
How does the closeness of an alpha particle’s approach to a nucleus affect its deflection?
A closer approach produces a larger deflection; a near head-on approach can produce backscattering.
Why were rare large deflections inconsistent with the plum pudding model?
The model had positive charge spread throughout the atom, rather than concentrated in a small nucleus.
Why did scientific models of atomic and nuclear structure change over time?
New evidence became available.
How did the plum pudding model represent an atom?
Positive charge was spread through the atom, with electrons embedded in it.
How did Rutherford’s nuclear model represent the distribution of positive charge and mass?
Positive charge and most of the mass were concentrated in a small central nucleus.
Before the neutron was discovered, which particles were sometimes thought to make up nuclei?
Protons and electrons.
Who discovered the neutron, and in what year?
Chadwick, in 1932.
What model of the nucleus did Chadwick’s discovery support?
Nuclei contain protons and neutrons.
Why can nuclei of the same element have different masses?
They have the same number of protons but different numbers of neutrons.