Nuclear Physics

Question 1

What is Nucleon?

Answer 1

• nucleon is the collective name for proton and neutron

Question 2

What is Nuclide?

Answer 2

• is a particular type of nucleus that is specified by its proton number and neutron number

Question 3

Nucleon number / Mass number

Answer 3

• number of nucleons found in the nucleus of an atom

Question 4

Atomic number / Proton number

Answer 4

• number of protons in the nucleus of an atom

Question 5

What are isotopes?

Answer 5

• two or more atoms of the same element, having the same number of protons but different numbers of neutrons in their nuclei

Question 6

Mass defect of an atom

Answer 6

• difference in mass between the mass of the constituent particles of an atom and the (smaller)mass of the whole atom

Question 7

Mass defect of a nucleus

Answer 7

• difference between the total mass of the separate nucleons and the combined mass of a nucleus
• mass defect = mass of constituent nucleons — mass of nucleus

Question 8

Einstein’s Equivalence

Answer 8

• there is equivalence between mass and energy, given by E = mc²

Question 9

What is the conservation of mass - energy

Answer 9

• total amount of energy, including energy that is equivalent to mass( E = mc² ) remains constant

Question 10

The Nuclear Binding Energy

Answer 10

• defined as the energy required to separate the nucleus into individual protons and neutrons
• defined as the energy released when a nucleus is formed from its constituent particles
• it is the energy equivalent of the mass defect of a nucleus
• Binding energy = (mass defect) x c²

Question 11

What is Nuclear Binding Energy per nucleon?

Answer 11

• it is the average energy required per nucleon to break down a nucleus into its constituent particles
• it is the average energy released per nucleon when a nucleus is formed from its constituent particles
• it is obtained by dividing the binding energy by the number of nucleons in the nucleus

Question 12

What is Nuclear Fusion?

Answer 12

• the formation of a larger nucleus from two nuclei of low nucleon number with the release of energy

Question 13

What is Nuclear Fission?

Answer 13

• the splitting of a nucleus of high nucleon number into two smaller nuclei of approximately equal mass with the release of energy and neutrons

Question 14

What is Radioactive Decay

Answer 14

• it is the spontaneous and random decay of a nucleus wth the emission of an alpha particle or a beta particle, and usually accompanied by the emission of a gamma ray photon

Question 15

What does spontaneous decay mean?

Answer 15

• it means the decay occurs by itself and is unaffected by environmental or external factors such as temperature and pressure

Question 16

What does random decay mean?

Answer 16

• it means the nucleus has constant probability of decay per unit time
• there is no way to predict when any individual nucleus will decay

Question 17

What is the radioactive decay constant?

Answer 17

• it is the probability of decay per unit time of a nucleus

Question 18

What is half-life?

Answer 18

• it is the average time taken for the activity of a particular radioactive nuclide to fall to half its initial value

Question 19

What is Count Rate?

Answer 19

• it is the number of emissions received by a detector per unit time from a radioactive source, which may include the background radiation

Question 20

What is Background count?

Answer 20

• it is the number of counts recorded by a radiation detector from background radiation detector from background radiation in the absence of a radioactive source

Question 21

Conservation of charge

Answer 21

• the atomic numbers of nuclides must be the same before and after the reaction

Question 22

Conservation of mass number

Answer 22

• mass numbers of nuclides must be the same before and after the reaction

Question 23

Conservation of mass-energy

Answer 23

• total amount of energy released/required must be the same as the difference in the total mass of the reactants and products

Question 24

Conservation of momentum

Answer 24

• total momentum before and after the reaction must be the same

Question 25

Biological effects of radiation

Answer 25

• radioactive materials that decay spontaneously produce ionising radiation, which has sufficient energy to strip away electrons from atoms or to break some chemical bonds
• any living tissue in the human body can be damaged by ionising radiation in a unique manner. The body attempts to repair the damage, but sometimes the damage is of a nature that cannot be repaired or it is too severe or widespread to be repaired
• mistakes in the natural repair process can lead to cancerous cells. The most common forms of ionising radiation are alpha and beta particles, gamma-ray