Nuclear Physics

Question 1

Nuclide

Answer 1

A nuclide is the atomic species with a specific mass number A and proton number Z

Question 2

Isotope

Answer 2

Isotopes are nuclides that have the same number of protons but different number of neutrons

Question 3

One atomic mass unit (1u)

Answer 3

Equal to one-twelfth of the mass of a carbon-12 atom

Question 4

The mass defect of a nucleus

Answer 4

The difference between the total mass of separate nucleons and the combined mass of the nucleus

Question 5

Nuclear Binding Energy (B.E = mc^2)

Answer 5

The energy equivalent of the mass defect of a nucleus, it is (the energy required to separate to infinity all the nucleons of a nucleus) divided by the (number of nucleons in the nucleus)

Question 6

Binding Energy per Nucleon

Answer 6

it is the total energy needed to completely separate all the nucleons in a nucleus to infinity divided by the number of nucleons in the nucleus

Question 7

Nuclear Fission

Answer 7

The splitting of a heavy nucleus into two nuclei of approximately the same mass

Question 8

Nuclear Fusion

Answer 8

Two light nuclei combines to form a nucleus of greater mass

Question 9

Why are nuclear reactions energetically favourable

Answer 9

Recall that the larger the binding energy per nucleon, the more stable the nucleus is, nuclei always tend towards the most stable nuclei, whose mass are around iron-56’s. As such, lighter nuclei undergo nuclear fusion until its mass number reaches 56 and heavier nuclei undergo nuclear fission until its mass reaches 56.

Question 10

Radioactivity/Radioactive decay

Answer 10

The process whereby a radionuclide is transformed into a more stable nuclide by emitting some forms of ionising radiation

Question 11

Explain why radioactive decay is random and spontaneous

Answer 11

Radioactive decay is random as it is impossible to predict which nucleus will decay next as the probability of decay per unit time is constant. This results in fluctuations in the count rate measured by a detector

Radioactive decay is spontaneous because the rate of decay/probability of decay of the nuclei is unaffected by any external factors such as temperature, pressure or chemical composition

Question 12

Activity of a radioactive source (A)

Answer 12

The number of radioactive decays per unit time/rate of radioactive decay in the source

Question 13

Half-life

Answer 13

The time taken for the number of undecayed nuclei to be reduced to half its original number