In Rutherford's α-particle scattering experiment, only a very small fraction of incident α-particles rebound or undergo very large-angle scattering. Consider the following statements.
A. The gold nucleus is extremely small compared with the size of the atom.
B. An α-particle and a gold nucleus carry equal positive charge.
C. Only a few α-particles have very small impact parameter.
D. Only a few α-particles have exceptionally large kinetic energy. E. Only a few α-particles undergo nearly head-on collisions with nuclei.
Which statements correctly explain the observation?

Question

In Rutherford's α-particle scattering experiment, only a very small fraction of incident α-particles rebound or undergo very large-angle scattering. Consider the following statements.

A. The gold nucleus is extremely small compared with the size of the atom.
B. An α-particle and a gold nucleus carry equal positive charge.
C. Only a few α-particles have very small impact parameter.
D. Only a few α-particles have exceptionally large kinetic energy. E. Only a few α-particles undergo nearly head-on collisions with nuclei.

Which statements correctly explain the observation?

G1 Physics · Accepted Answer

Large-angle or backward scattering requires an α-particle to pass extremely close to the positively charged nucleus. Statement A is correct: the nucleus occupies a very small fraction of the atomic volume, so encounters with the nuclear region are rare. Statement B is false: an α-particle has charge +2e, whereas a gold nucleus has charge +79e. Statement C is correct: only a small fraction of incident particles have sufficiently small impact parameter to approach the nucleus closely. Statement D…