Question

Each nucleus has a “binding energy per nucleon” value. What does this mean? How do these values relate to radioactive decay?

Describe the significant experimental contribution made to our understanding of atomic and nuclear physics by one of these scientists: You may choose...either Millikan or Rutherford. Tell in your own words what they did and what they learned.

Answer 1

Each nucleus has a "binding energy per nucleon", this means that the energy which is binding the nucleons inside the nucleus. It is the minimum energy required to disassemble the nucleus of the atom into its components(nucleons). The maximum the B.E per nucleon, the more stable is the nucleus.

Radioactive decays involve alpha, beta, gamma decay. These happen because of the unstability of the nucleus which is due to less B.E per nucleon of any nucleus.

Rutherford in 1909, performed Gieger-Marsden Experiment also known as Gold Foil Experiment in which he demonstrated that the atom ha a tiny and heavy nucleus. In the experiment he used alpha particles to penetrate through the gold foil and he observed that most of the alpha particle passed through the gold foil and a very less got scattered and 1% retraced it path. This resulted in that there is small and and heavy nucleus is present. He proved J.J Thomson theory of atomic structure wrong.we can say that it was the first step towards understanding the concept of atomic physics. Through this experiment(Rutherford scattering) various parameters were calculated such as differential cross-section, impact parameter etc.

Results of Rutherford Gold Foil Experiment:

A)An electrically neutral sphere with

1) A small and positively charged nucleus at the center

2) Surrounded by revolving electrons in their dynamically stable orbits

B)The centripetal force that keeps the electrons in their orbits is an outcome of:

• The electrostatic force of attraction between - The positively charged nucleus and the negatively charged revolving electrons.

Hence, for the start Rutherford gave an overview in understanding the atomic and nuclear physics.