Semi empirical mass formula

Question 1

What our the five terms in the equation

Answer 1

Volume term, surface term, coulomb term, symmetry term and pairing term

Question 2

Volume term

Answer 2

Has linear relationship with the number of nucleons A in a nucleus, such that wehn considering the binding energy per nucleon B/A this corresponds to a constant for all nuclei. This is related to the range of the nucleon-nucleon interaction and the fact that the density (and thus number of neighbouring nuclei) is rather constant for all nuclei.

Question 3

Surface Term

Answer 3

Takes into account that nucleons at the surface of the nucleus have less neighbours and thus their contribution to their binding energy is less. It has a dependency on the mass number as A^2/3, which is a term proportional to the surface of a sphere with radius A^1/3

Question 4

The Coulomb term

Answer 4

takes into account the repulsion between the positively charged protons, which also reduces the binding energy of the nucleus. It has a dependency on Z^2

Question 5

The Symmetry Term

Answer 5

Takes into account that nuclei with about the same number of protons and neutrons tend to be more stable. This term is important for light nuclei and becomes less important for more heavier ones. Where the increased number of protons increases the coulomb repulsion. This term can be considered as containing the quantum mechanical effects on the binding energy and in particular the Pauli principle for fermions.

Question 6

The pairing term

Answer 6

reflects the tendency of like nucleons to couple pairwise and reflects the fact that nuclei with even Z and even N numbers are more stable.