Chapter 22

Question 1

What are protons?

Answer 1

Protons are positively charged nucleons with the same size charge as an electron

Question 2

What are neutrons?

Answer 2

Neutrons are electrically neutral nucleons, slightly more massive than protons

Question 3

What is the atomic number?

Answer 3

Atomic number (Z) is the number of protons in the nucleus of an atom

Question 4

What is the mass number?

Answer 4

Mass Number (A) is the number of protons plus neutrons in the nucleus of an atom

Question 5

What are isotopes?

Answer 5

Isotopes are atoms of a given (the same/a particular) atomic number but different atomic mass (due to different number of neutrons)

Question 6

What is radioactivity?

Answer 6

Radioactivity is the (spontaneous) disintegration of a nucleus with the emission of (alpha, beta and/or gamma) radiation

Question 7

What is radiation?

Answer 7

Radiation is the emission of particles of matter or photons of energy

Question 8

What is ionisation?

Answer 8

Ionisation is the charging of a neutral atom or molecule when it loses or gains one or more electrons

Question 9

What is penetration?

Answer 9

Penetration is the distance the (nuclear) radiation travels through a medium

Question 10

What is a radioisotope?

Answer 10

A radioisotope is an unstable isotope of an element that spontaneously disintegrates (decays), emitting radiation (alpha, beta and/or gamma)

Question 11

What is alpha emission?

Answer 11

Alpha emission is the emission of a helium nucleus from a large atom

Question 12

What is beta emission?

Answer 12

Beta emission is the emission of an electron when a neutron decays into a proton

Question 13

What is gamma emission?

Answer 13

Gamma emission is the emission of high energy photons from an unstable nucleus

Question 14

What is the activity of a radioactive source?

Answer 14

The Activity (A) of a radioactive source is the rate of emissions from that source

Question 15

State the Law of Radioactive Decay

Answer 15

The activity of a radioactive source is proportional to the number of undecayed nuclei present

Question 16

What is the half-life?

Answer 16

The half-life of a radioactive isotope is the time taken for half of the nuclei in a given sample to decay

Question 17

What is fission?

Answer 17

Fission is the splitting of a large nucleus into two smaller nuclei of roughly equal mass, with the emission of neutrons and release of energy

Question 18

What are chain reactions?

Answer 18

Chain reactions are where at least one neutron is released during each fission reaction. These released neutrons cause more fission when absorbed by another nucleus causing a self-sustaining reaction

Question 19

What is the critical mass?

Answer 19

The minimum amount of the fissile material needed in order to cause a chain reaction

Question 20

What is fusion?

Answer 20

Nuclear fusion is the combining of two small nuclei to form a single larger nucleus with the release of energy

Question 21

What is background radiation?

Answer 21

Background radiation is that which comes from environmental sources including the Earth’s crust, the atmosphere, cosmic rays and radioisotopes