Atomic and Nuclear Physics

Question 1

The nucleus of an atom contains protons and electrons

Answer 1

False (The nucleus contains protons and neutrons, while electrons orbit around it in shells)

Question 2

Protons have a positive charge, equal in magnitude but opposite in charge to electrons

Answer 2

True (Protons + Electrons -)

Question 3

Neutrons have no electric charge but have roughly the same mass as protons

Answer 3

True (Bonus: electrons have a much smaller mass)

Question 4

The atomic number (Z) represents the total number of protons and neutrons in an atom

Answer 4

False (The atomic number Z represents only the number of protons; Mass Number (A) represents the number of protons and neutrons)

Question 5

The number of protons within a nucleus (Atomic Number) determines what element it is

Answer 5

True

Question 6

Isotopes of an element have the same atomic number but different mass numbers

Answer 6

True

Question 7

The mass of a nucleus is equal to the mass of its component parts (protons + neutrons)

Answer 7

False (Some of the mass contributes to binding energy of the nucleus)

Question 8

Nuclear fusion releases energy by splitting atoms

Answer 8

False (fusion releases energy by joining atoms, while fission releases energy by splitting them)

Question 9

Unstable nuclei tend to have an equal number of protons and neutrons

Answer 9

False (Stability is influenced by proton-neutron ratios, usually favouring even numbers of protons or neutrons)

Question 10

Nuclei of certain isotopes are unstable and contain excess energy

Answer 10

True

Question 11

Unstable isotopes revert to more stable states by releasing energy in the form of radiation. What is this process called?

Answer 11

Radioactive Decay / Radioactivity

Question 12

What are the three main types of radioactivity?

Answer 12

• Alpha-Particles
• Beta-particles
• Gamma rays

Question 13

Alpha particles consist of two protons and two neutrons (and are identical to helium nuclei)

Answer 13

True

Question 14

Alpha particles are highly penetrating

Answer 14

False (Alpha particles are heavy and have very little penetrating power)

Question 15

Despite their short path length, alpha particles can cause large amounts of ionisation within tissue due to their large mass

Answer 15

True

Question 16

The main risk with alpha emitters is from inhalation or digestion

Answer 16

True (eg. Radon Gas)

Question 17

Beta-particles are electrons emitted from the nucleus when a neutron converts to a proton

Answer 17

True

Question 18

In beta emission, a neutron transforms into a proton and causes an electron to be emitted from the orbital shells

Answer 18

False (In beta emission, the electron is emitted from the nucleus, not from the orbital shells)

Question 19

Beta-decay increases the atomic number of an element by 1

Answer 19

True (due to addition of proton)

Question 20

Beta-particles travel further in tissue and require greater shielding than alpha-particles

Answer 20

True

Question 21

Beta-particles cause more ionisation in tissues than alpha-particles

Answer 21

False (Beta-particles cause less ionisation in tissues than alpha particles)

Question 22

Gamma rays are a form of electromagnetic radiation with energy levels similar to X-rays

Answer 22

False (gamma-rays have much higher energy than X-rays)

Question 23

Beta-decay involves Weak Nuclear Force

Answer 23

True

Question 24

Gamma rays are often emitted alongside alpha or beta particles as the nucleus sheds excess energy

Answer 24

True

Question 25

The Radioactive Decay Law states that the rate of decay is proportional to the number of nuclei present

Answer 25

True

Question 26

The decay of a radionuclide can be characterised by its half-life T1/2

Answer 26

True

Question 27

What is half-life T1/2?

Answer 27

The time it takes for half the nuclei in any sample to decay