Unit 4

Question 1

Describe the plum pudding model

Answer 1

A sphere of positive charge with electrons spread throughout it

Question 2

Describe how an electron can move between energy levels

Answer 2

An electron can move into a higher energy level by absorbing EM radiation
It can also move into a lower energy level by emitting EM radiation

Question 3

What’s the type of particle created when an atom loses or gains electrons

Answer 3

ion

Question 4

Describe how the subatomic particles are arranged in a nuclear model of an atom

Answer 4

The protons and neutrons are in the central nucleus and the electrons around the nucleus arranged in shells

Question 5

An atom has 26 protons. State the number of electrons and explain why

Answer 5

26 electrons. Atoms in neutral. Protons and electrons have equal but opposite charges. For these charges to cancel there must be the same number of each

Question 6

Define ionisation

Answer 6

An atom losing or gaining at least one electron electron

Question 7

An electron is emitted from a nucleus. Explain the effect this has on the mass number and atomic number of the nucleus

Answer 7

The atomic number increases but the mass number stays the same. This is because emitting an electron involves a neutron turning into a proton

Question 8

A student writes a nuclear Decay equation but he gets it wrong. How could he get it wrong

Answer 8

Have an equal atomic numbers on each side

Question 9

Define half-life in terms of count rate

Answer 9

The time taken for the count rate of a sample to half

Question 10

A Student predicts the activity of a sample for 500 million years in advance. Why is he likely to be wrong

Answer 10

Radioactive Decay is random and the effect of randomness on the activity will be greater for lower activities

Question 11

Suggest two methods that workers could use to reduce their exposure to radiation in a radioactive power plant

Answer 11

Wearing protective suits

Using remote control arms

Question 12

State the name given to the amount of radiation that an individual is exposed to

Answer 12

Radiation dose

Question 13

State two things that can affect the amount of radiation that an individual is exposed to

Answer 13

Location and job

Question 14

Explain the difference between contamination and irradiation

Answer 14

Contamination is where radioactive particles get onto an object. Irradiation is where an object is exposed to radiation

Question 15

Give two ways in which a scientist can protect yourself against contamination when handling a radioactive sample

Answer 15

Wearing a protective suit and wearing gloves

Question 16

Explain why an alpha emitter would not be used for medical imaging

Answer 16

Alpha radiation will be too dangerous inside the body I would not be detectable outside the body as it cannot penetrate tissue

Question 17

Explain why an isotope with a short half-life must be used for medical imaging

Answer 17

A short half-life means the activity will quickly drop so the patient will not be exposed to radiation for too long

Question 18

What occurs during nuclear fusion

Answer 18

A heavier nucleus is formed by joining two lighter nuclei which converts mass into energy

Question 19

State one similarity between nuclear fusion and nuclear fission

Answer 19

They both release energy

Question 20

State one difference between nuclear fusion and nuclear fission

Answer 20

Station is the splitting of a large nucleus to form a smaller nuclei where is fusion is the joining of smaller nuclei to form a larger one

Question 21

Explain how the absorption of a neutron can lead to a chain reaction in a fission reactor

Answer 21

Absorbing a neutron makes the nucleus more unstable. The unstable nucleus undergoes fission. Patient is the splitting of an unstable nucleus into two lighter elements releasing 2 or 3 neutrons. These neutrons can be absorbed by other nuclei causing more fission. Each Decay can cause another to happen which is a chain reaction.

Question 22

What is nuclear fission

Answer 22

The splitting of an unstable nucleus into two lighter elements and releasing 2 or 3 neutrons

Question 23

Explain what would happen if a chain reaction is uncontrolled

Answer 23

Each fission Decay releases energy, so an uncontrolled chain reaction would release lots of energy which could lead to an explosion