The development of the model of the atom

Which of the following was investigated by the large-angle alpha particle scattering experiment?

Over one hundred years ago, Rutherford supervised a series of experiments using a source of alpha particles and thin gold foil.

Describe the model of the atom that Rutherford proposed as a result of this series of experiments.

The initial kinetic energy of an alpha (⁴₂α) particle is 7.310⁻¹³J.

In a textbook, it states that an alpha particle with this energy would be brought to rest when it reached a distance of 5.010⁻¹⁴m from the centre of the

Deduce whether this statement is correct.

Determine the initial momentum of the alpha particle.

An alpha particle moves along a path directly towards a gold nucleus, as shown.

An elastic interaction occurs and the alpha particle recoils.

State what is meant by an elastic interaction.

State what happens to the atoms in the gold foil as a result of these interactions.

Questions 8 and 9 refer to the information below.

Alpha particle scattering investigations were first carried out in the early part of the 20th century.

The diagram shows the path of an α particle that is being deflected by the nucleus of a gold atom. The closest distance of approach of the α particle to the nucleus is at point P.

8 Which row in the table describes the speed and potential energy of the α particle at point P on this path?

Questions 8 and 9 refer to the information below.

Alpha particle scattering investigations were first carried out in the early part of the 20th century.

The diagram shows the path of an α particle that is being deflected by the nucleus of a gold atom. The closest distance of approach of the α particle to the nucleus is at point P.

9 Which of the following can be concluded about a gold atom from the deflection of this α particle?

*4 Alpha particle scattering experiments led Rutherford to propose the nuclear model of the atom. Alpha particles were directed towards a thin gold foil.

Describe how evidence from these experiments supports the nuclear model of the atom.

Questions 9 and 10 refer to the information below.

Alpha particle scattering investigations were first carried out in the early part of the 20th century.

10 Which of the following conclusions could not be made as a result of these investigations?

At the beginning of the 20th century, Rutherford carried out large-angle alpha particle scattering experiments using gold (¹⁹⁷₇₉Au) foil. The vast majority of the alpha particles went straight through the foil whilst a few were deflected straight back.

Describe how the model of the atom changed, as a consequence of these experiments.

In one experiment the alpha particles had an initial energy of 7.7 MeV.

Calculate the distance of closest approach of the alpha particles to the nucleus of a gold atom. Assume that the gold nucleus remains at rest.

Rutherford also carried out the experiment with aluminium (₁₃²⁷Al) foil. The aluminium foil had the same thickness as the gold foil and the alpha particles had the same initial kinetic energy.

The following observations were made.

Observation 1: The fraction of alpha particles scattered at any particular angle for aluminium foil was always much less than for gold foil.

Observation 2: The alpha particles scattered from aluminium foil had less kinetic energy than the alpha particles scattered from gold foil.

Explain how these observations can be used to deduce how an aluminium nucleus compares to a gold nucleus.

The diagram shows a model used to demonstrate alpha particle scattering. A ball bearing is set rolling on a wooden track. The track is positioned so that the ball bearing rolls onto a metal sheet with a curved surface known as a ʻhillʼ.

The diagram shows a vertical cross-section through the hill. The surface is curved so that the height of a point h on the curved surface is inversely proportional to the distance r from the centre of the hill.

Explain why the hill is suitable as a model for the electric field surrounding the nucleus of an atom.

A plan view of the arrangement is shown.

The wooden track is moved to different positions and the ball bearing is released.

Describe the results of the alpha particle scattering experiment and how these can be demonstrated by moving the wooden track to different positions.

The diagram shows a model used to demonstrate alpha particle scattering. A ball bearing is set rolling on a wooden track. The track is positioned so that the ball bearing rolls onto a metal sheet with a curved surface known as a ʻhillʼ.

The diagram shows a vertical cross-section through the hill. The surface is curved so that the height of a point h on the curved surface is inversely proportional to the distance r from the centre of the hill.

Explain why the hill is suitable as a model for the electric field surrounding the nucleus of an atom.

A plan view of the arrangement is shown.

The wooden track is moved to different positions and the ball bearing is released.

Describe the results of the alpha particle scattering experiment and how these can be demonstrated by moving the wooden track to different positions.

The alpha particle scattering experiment led to a number of observations and conclusions.

Which row in the table gives a correct observation and corresponding conclusion from