Nuclear physics

Question 1

atom

Answer 1

The smallest unit of an element, made from neutrons, protons and electrons.

Question 2

alpha particles

Answer 2

A particle made from two protons and two neutrons, the same as a He nucleus, emitted as radioactive decay.

Question 3

Nuclide

Answer 3

An atom or nucleus characterised by a specific number of protons and neutrons.

Question 4

Nuclide notation

Answer 4

A notation using symbols for elements along with atomic number and nucleon number to describe the composition of an element’s nucleus.

Question 5

periodic table (lol)

Answer 5

A list of the elements in ascending order of atomic number reading left to right then down the page.

Question 6

proton number

Answer 6

The number of protons in a nucleus.

Question 7

atomic number

Answer 7

The number of protons in a nucleus.

Question 8

mass number

Answer 8

The total number of protons and neutrons in the nucleus, also the total relative mass of the nucleus.

Question 9

nucleus

Answer 9

is the centre of an atom, it contains protons and neutrons.

Question 10

electrons

Answer 10

are charged particles that orbit the nucleus.

Question 11

nucleon number

Answer 11

is equal to the total relative mass of the nucleus.

Question 12

ion

Answer 12

is a charged atom or particle.

Question 13

isotope

Answer 13

is an element with a different number of neutrons to the most commonly found version.

Question 14

Nuclear fusion

Answer 14

is the process in which light nuclei join together.

Question 15

Nuclear fission

Answer 15

is the process in which heavy nuclei break apart.

Question 16

background radiation

Answer 16

originates from both man-made and natural sources.

Question 17

The activity of a radioactive sample is given as

Answer 17

count rate (counts/s).

Question 18

The emission of radiation

Answer 18

is spontaneous and in a random direction.

Question 19

The three types of decay

Answer 19

Alpha, beta and gamma

Question 20

Radioactive decay

Answer 20

is a change in an unstable nucleus. The unstable nucleus emits radiation to become more stable.

Question 21

Half life

Answer 21

is the time taken for half the nuclei to decay.

Question 22

How can radioactive sources affect organisms

Answer 22

can damage living tissue leading to mutations, cell death and cancer. Moving and storing radioactive sources needs to be done in a way that reduces risk due to the penetrative abilities of the radiation.

Question 23

Alpha ( α ) particles

Answer 23

An alpha particle is made up of two protons and two neutrons. The mass of each nucleon is 1, so the total mass is 4. Two protons give the α-particle a charge of +2. Due to its large mass and charge, an α particle is highly ionising.

Alpha particles are the least penetrating of all the three types of radiation. They will only travel about 5 cm through air and are stopped by materials such as thin paper or skin.

Question 24

Beta ( β ) particles

Answer 24

A beta particle is a high-energy electron.

A β -particle has almost no mass (relative mass = 1/2000)
and a charge of –1. As a result, a β -particle does not always displace electrons from their orbit when it collides with an atom and so is only mildly ionising.

Beta particles can travel through skin but are stopped by a few millimetres of aluminium (aluminium foil).

Question 25

Gamma ( γ ) emissions

Answer 25

Electromagnetic waves emitted by radioactive materials. Gamma emissions have no mass and no charge, so are weakly ionising. Gamma emissions are the most penetrating of the three types of radiation and can only be stopped by thick lead or concrete.

Question 26

Penetrating abilities of radiation

Answer 26

Alpha particles, beta particles and gamma emissions have different properties, ionising effects and penetrating abilities. The penetrating ability is how capable each type of radiation is of travelling through objects.

Question 27

ionising affects and penetrating ability of alpha gamma and beta

Answer 27

alpha: High Weak Beta: Mild Mild Gamma: weak High

Question 28

Deflecting alpha emissions

Answer 28

Alpha particles have a charge of +2 which means they are repelled by the positive plate and attracted to the negative plate. Only deflected by a small amount as it has a larger mass compared to it's charge.

Question 29

Deflecting beta emissions

Answer 29

Beta particles have a charge of -1 which means it is attracted to the positive plate as it is deflected by the negative plate. Deflected by a large amount as it has a small mass compared to it's charge

Question 30

Deflecting gamma emissions

Answer 30

Gamma emissions are radioactive waves meaning they have no charge so their path is not altered of the presence of an electric field and so just travel straight through

Question 31

activity

Answer 31

The rate at which an unstable nucleus decays

Question 32

Becquerel

Answer 32

The unit of radioactive activity.

Question 33

Bohr model

Answer 33

A model of the atom that suggested that electrons orbit the nucleus at set distances.

Question 34

Chain reaction

Answer 34

The process of neutrons released by a fission reaction, being absorbed by another unstable, large nuclei, and inducing further fission.

Question 35

Energy levels

Answer 35

The stable states in which electrons are found in around a nucleus. Electrons can transition to a higher energy level through the absorption of electromagnetic radiation and can transition to a lower energy level through the emission of electromagnetic radiation.

Question 36

Fission products

Answer 36

Fission produces two smaller nuclei, two or three neutrons and gamma rays. All these products are released with kinetic energy.

Question 37

Gamma ray

Answer 37

Electromagnetic radiation emitted from a nucleus. Geiger-Muller Tube: A detector that measures the count-rate of a radioactive sample.

Question 38

Ions

Answer 38

Atoms with a resultant charge due to the loss or gain of electrons. Irradiation: The process of an object being exposed to nuclear radiation. The object doesn’t become radioactive.

Question 39

isotope

Answer 39

Atoms with the same number of protons but different numbers of neutrons. The atomic number is the same, but the mass number is different.

Question 40

Negative ions

Answer 40

Atoms that gained electrons and so have a resultant negative charge.

Question 41

neutrons

Answer 41

A neutrally charged constituent of the nucleus.

Question 42

Nuclear Explosions

Answer 42

Nuclear explosions in nuclear weapons are caused by an uncontrolled chain reaction which results in vast quantities of energy being produced in a very small period of time.

Question 43

Plum Pudding Model

Answer 43

An old model of the atom that represented the atom as a ball of positive charge, with negative charges distributed throughout it.

Question 44

positive ions

Answer 44

Atoms that have lost electrons and so have a resultant positive charge.

Question 45

protons

Answer 45

A positively charged constituent of the nucleus.

Question 46

Radioactive Contamination

Answer 46

The unwanted presence of radioactive atoms on other materials. It is hazardous due to the decay of the contaminating atoms.

Question 47

Sieverts

Answer 47

: The unit used for radiation dosage.

Question 48

Spontaneous fission

Answer 48

Fission that occurs without the absorption of a neutron. Spontaneous fission is rare and in most cases, fission is induced with a neutron.