Chapter 4: Particles in the nucleus

Question 1

4A:

Define a nucleon

Answer 1

A particle that is found in the nuclei of an atom is labeled as a “nucleon.”

Question 2

4A:
Define a quark

Answer 2

A particle of which all nucleons are composed of.

Question 3

4A:
Define the “strong nuclear force.”

Answer 3

The strong nuclear force is a fundamental force that holds quarks together within nucleons and yields a bind between the nucleons in a nuclei.

Question 4

4A:
Define the “electrostatic force,” as it relates to the nucleus.

Answer 4

The electrostatic force within the nucleus creates a repulsion between the protons in a nucleus.

Question 5

4A:
Explain when a nucleus will be stable

Answer 5

If the nucleus has an atomic number below 20 then there must be an equal number of protons to neutrons for nuclear stability to be allowed.

However, if a nucleus has an atomic number between 20 and 83 then there must be a greater number of neutrons (than protons) in the nucleus for the strong nuclear force to counteract the electrostatic force repelling protons in the nucleus for it to be stable.

Question 6

4A:
List some reasons for nuclear instability

Answer 6

1: Too many protons in the nucleus. This means the electrostatic force-repelling protons will counteract the strong nuclear force attracting nucleons within the nucleus.

2: Too many neutrons per proton in the nucleus. As neutrons need to exist in higher states of energy.

3: The atomic number of the nucleus is greater than 83, making the nuclei inherently unstable.

Question 7

4A:
Define the “weak nuclear force.”

Answer 7

The weak nuclear force is responsible for beta decay in a nucleus as it changes the properties of quarks.

Question 8

4B:
Define the term “half life.”

Answer 8

The half-life is defined as the time taken for half a radioactive sample to decay.

Question 9

4B:
Define “radioactive decay.”

Answer 9

The process of an unstable isotope becoming stable through losing energy and emitting either a particle or photons.

Question 10

4B:
Define “activity.”

Answer 10

Activity is defined as the rate at which a radioactive sample is decaying per unit of time. So, how many radioactive decays are occurring per a specified unit of time?

Question 11

4C:
Define the “parent nuclei.”

Answer 11

The parent nucleus is the initial nucleus (which is unstable) before the occurrence of any radioactive decay.

Question 12

4C:
Define the “daughter nucleus.”

Answer 12

The daughter nucleus is the new nuclei formed after the initial nucleus has decayed, which is more stable than the parent nuclei, but not guaranteed to be wholly stable itself.

Question 13

4C:
Define “alpha decay.”

Answer 13

Alpha decay is the process of an unstable nucleus decaying into a more stable nucleus via the emission of an alpha particle.

Question 14

4C:
Define an “alpha particle.”

Answer 14

An alpha particle consists of two protons and two neutrons, resembling a helium nucleus.
Emitted via alpha decay.

Question 15

4C:
List some of the properties of “alpha decay.”

Answer 15

: They are relatively heavy with an atomic mass of 4.
: They travel 5%-7% of the speed of light and are not penetrating particles.

Question 16

4C:
Why does alpha decay occur?

Answer 16

Alpha decay will occur when there are too many protons in a nuclei, which is the reason for the instability in the first place.

Question 17

4C:
Define “beta plus decay.”

Answer 17

Beta plus decay entails unstable nuclei decaying into a more stable isotope through the emission of a positron and a neutrino, whilst also transforming a proton into a neutron.

Beta plus decay will occur due to an excess of protons in the nuclei.

Question 18

4C:
Define “beta minus decay.”

Answer 18

Beta minus decay entails unstable nuclei decaying into a nucleus which is more stable through the emission of an electron and an anti-neutrino, and via the transformation of a neutron into a proton.

Beta minus decay results from nuclei having too many neutrons per proton to achieve stability.

Question 19

4C:
List some of the properties of beta radiation.

Answer 19

: Beta particles are incredibly light.
: Beta particles travel at quick speeds-90% the speed of light.
: Beta particles have extreme penetrating powers.

Question 20

4C:
Define “Gamma decay.”

Answer 20

Gamma decay occurs when a nucleus is in an excited state of energy and decays into more stable nuclei (note there is no change between the parent nuclei and the daughter nuclei) through the emission of gamma radiation.

Question 21

4D:
Define “radiation.”

Answer 21

The transmission of energy from one location to another though EM radiation or high-speed particles.

Question 22

4D:
Define a “tissue.”

Answer 22

A tissue is a group of specialized cells.

Question 23

4D:
Define “Ionization.”

Answer 23

Ionization is defined as the process of an electrically neutral atom becoming charged due to the gain or loss of an electron.

Question 24

4D:
Define “ionizing impact.”

Answer 24

The ionizing impact is defined as the ability of ionization to damage cells.

Question 25

4D:
Compare the ionizing abilities of Alpha radiation when absorbed from outside and within the body.

Answer 25

When alpha radiation is absorbed from outside the body it has no ionizing impact, as alpha particles cannot penetrate the skin due to their mass.

However, when alpha radiation is absorbed from within the body it can have great levels of ionizing impact.

Question 26

4D:
Compare the ionizing abilities of Beta radiation when absorbed from outside and within the body.

Answer 26

When Beta radiation is absorbed from outside the body there is a level of ionizing ability on surface-level tissues like eyes, as Beta particles can penetrate the skin.

However, when Beta radiation is absorbed from within the body there is a greater level of ionizing impact.

Question 27

4D:
Compare the ionizing abilities of Gamma radiation when absorbed from outside and within the body.

Answer 27

When Gamma radiation is absorbed from outside the body it has high levels of ionizing impact due to its extreme powers of penetration.

However, when Gamma radiation is absorbed from within the body it has no ionizing impact as it will pass out un-deflected due to its penetrating powers.

Question 28

4D:
Describe the capacity for Alpha particles to cause cell damage.

Answer 28

Alpha particles will impact a small range of cells when absorbed within the body. However, due to their extremely high levels of Ionizing impact, they will cause cells to be killed.

Question 29

4D:
Describe the capacity for Beta particles to cause cell damage

Answer 29

Beta particles will impact a larger range of cells than Alpha particles absorbed. However, their ionizing impact is less than that of Alpha particles but still high, meaning they will cause cell damage and potentially death.

Question 30

4D:
Describe the capacity for Gamma radiation to cause cell damage.

Answer 30

Gamma radiation passes through the body mostly un-deflected due to its extreme powers of penetration. Hence, its ability to cause cell damage is low, meaning only minimal damage will be done to cells.

Question 31

4D:
Define the “absorbed dose.”

Answer 31

The absorbed dose measures the radiation absorbed per unit of mass of a tissue and is measured in Gray (GY).

Question 32

4D:
Define the “equivalent dose.”

Answer 32

The equivalent does measures the energy absorbed and takes into account the type of radiation and its damage on the human body.

It reflects the biological damage on a tissue due to the absorption of a particular type of radiation. Measured in SV.

Question 33

4D:
Define the “radiation weighting factor.”

Answer 33

The radiation weighting factor shows the biological effect of each type of radioactive decay on the human body.

Alpha decay: 20
Beta decay (Plus and minus): 1
Gamma decay: 1

Question 34

4D:
Define the “effective dose.”

Answer 34

The effective dose measures the energy a tissue absorbs and reflects the sensitivity of different organs to radiation from the nucleus. It is measured in SV.

Question 35

4D:
Define the “tissue weighting factor.”

Answer 35

The tissue weighting factor shows the sensitivity of different organs to the absorption of radiation from the nucleus.

Question 36

4D:
Explain how Alpha radiation is used in medical therapies

Answer 36

This process is known as “targeted alpha decay,” and entails alpha compounds entering the human body and emitting alpha particles, which kill damaged cells and stop them from reproducing.

Question 37

4D:
Explain how Beta radiation is used in medical therapies.

Answer 37

Sources of Beta decay are placed in “radioactive seeds,” and these seeds enter the human body in affected areas. Given Beta particles can penetrate, they will damage the affected cells they’re placed near.

Question 38

4D:
Explain how Gamma radiation is used in medical therapies.

Answer 38

Gamma rays emitted via Gamma decay have extreme powers of penetration and speed, meaning they are used for the imaging of impacted areas as they can travel through the body without deflection and not cause damage to cells.