P7: Radioactivity (Y11 - Autumn 2)

Question 1

❌ How were Radioactive materials discovered

Answer 1

Henri Bacquerel’s used covered photigraphic plages that were placed inder Uranium salts to discover radioactivity

Henri Bacquerel’s work was expanded on by Marie and Pierre Curie who investigated and discovered a range of new radioactive elements

Question 2

❌ What is the definition of Radiation?

Answer 2

Radiation is the emission of energy as electromagnetic waves or as moving subatomic particles.

Question 3

❌ What makes things Radioactive

Answer 3

Most atoms have stable nuclei - they don’t change over time.

Unstable nuclei are at the heart of radioactivity. They are unstable due to:

• Too many protons
• To many neutrons
• Being too large

These factors lead to the nucleus having some excess of energy that makes it unstable. They can undergo nuclear decay, emitting radiation and becoming more stable as they do.

(Radioactive substances emit radiation no matter what is done to them)

Question 4

🟠 What is the unit for Radioactivity?

Answer 4

Radioactivity has units of becquerels (Bq), where 1Bq = 1 nuclear decay event per second.

Question 5

🟠 What is a Geiger Counter and what does it do?

Answer 5

A Geiger counter is an instrument used for detecting and measuring ionizing radiation.

When alpha, beta or gamma radiation enters the tube it produces ions in the gas. The ions created in the gas enable the tube to conduct. A current is produced in the tube for a short time. The current produces a voltage pulse. Each voltage pulse corresponds to one ionising radiation entering the GM tube. The voltage pulse is amplified and counted.

Question 6

🟠 Why does a Geiger Counter click even when it is not near a radioactive source.

Answer 6

A Geiger counter clicks when it is not near a radioactive sources.

This effect is due to background radiation. This radiation is from radioactive substances:

• In the environment (such as the air)
• From space (cosmic rays)
• From devices such as x-ray tubes.

Question 7

🟠 What are the 3 types of Radiation

Answer 7

• Alpha Radiation (α)
• Beta Radiation (β)
• Gamma Radiation (γ)

Question 8

🟠 What is Radioactivity

Answer 8

Radioactivity is when an atom becomes unstable when the nucleus spontaneously decay into other smaller neclei’s and emit radiation.

Question 9

❌ Who came up with the idea of Atoms and wh came up with the Pulm Pudding Model

Answer 9

Back in ancient Greece, philosophers came up with the idea of everything being made of tiny, indivisible particles they called atoms.

After the discovery of the electron as being a subatomic particle in atoms, J. J. Thomson came up with the Plum Pudding Model of the atom in 1904.

Electrons buried inside the atom which is made up of positively charged material

Question 10

❌ How is the Nuclear Model different to the Plum Pudding Model

Answer 10

This model is different because nuclear model includes a small central nucleus which is positively charged, containing protons and neutrons. This nucleus is surrounded by electrons which orbit around the nucleus in orbitals (electron shells)

Question 11

❌ How did Rutherford discover the Nucleus

Answer 11

Ernest Rutherford fired beams of alpha particles towards gold foil.

Most alpha particles passes through, however around 1 in 8000 bounced right back. This meant he realised that there would’ve been a dense positively charged nucleus, with the rest of the atom being sparce (less dense) which were made up of electrons

Question 12

❌ What does the fact that most Alpha particles travel through the foil undefelected show?

Answer 12

The majority of the atom is empty space, made up of shells which electrons orbit

Question 13

❌ What does the fact that some Alpha particles are deflected by small angles show?

Answer 13

The is a positively charged mass in the centre, known as the nucleus (because it repelled the particles)

Question 14

❌ What does the fact that, ocasionally, an aplga particle trafels back from the foil show?

Answer 14

There is a very dense central mass, now known as the nucleus

Question 15

❌ 1. Explain why might alpha particles be deflected

2. Explain why might alpha particles pass through the foil layer?
3. Why might alpha particles be reflected back?

Answer 15

• Alpha particles are positively charged
• The Nucleus of an atom is also positively charged
• These charges can repel each other changing the direction of the alpha particle.
• Most of the atom is made of space and so some alpha particles just pass straight through.
• Rarely some alpha particles hit the Nucleus and repel back.

Question 16

🟠 What is a Radioisotope?

Answer 16

A radioisotope is an isotope which has and unstable nucleus. It will decay by emitting radiation.

Question 17

🟠 What is an Alpha Emission (What’s an Alpha Particle)

Answer 17

As an alpha (α) particle is made up of two protons plus two neutrons. Its relative mass is 4, and its relative charge is +2. So it is usually represented by the symbol 4|2 α (Mass Number|Atomic Number). It is identical to a helium nucleus, so in nuclear equations, you may see it as 4|2 He

(Alpha (α) – an atom decays into a new atom and emits an alpha particle (2 protons and 2 neutrons)

Alpha radiation is the nucleus of a helium atom travelling at extremely high speed.)

Question 18

🟠 What happens when an unstable nucleus emiuts an Alpha Particle?

Answer 18

• It’s atomic number goes down by 2, and its mass number goes down by 4
• The mass and the charge of the nucleus are both reduced

For example, the thorium istope 228|90 Th decays by emitting an α particle. So it forms the radium isotope 224|88 Ra.

Question 19

🟠 What is an Beta Emission (What’s an Beta Particle)

Answer 19

A Beta (β) particle is an electron created and emitted by a nucleus that has too many neutrons compared with its protons. A neutron in the nucleus changes into a proton and a β particle (i.e an electron), which is instantly emitted. The relative mass of a β particle is effectively zero, and its relative charge is -1. So a β particle can be represented by the symbol 0|-1 β

(Beta (β) – an atom decays into a new atom by changing a neutron into a proton and electron.

The fast moving, high energy electron is called a beta particle.)

Question 20

🟠 What happens when an unstable nucleus emits an Beta Particle?

Answer 20

• The atomic number of the nucleus goes up by 1, and its mass number is unchanged (because a neutron changes into a proton)
• The charge of the nucleus is increased, and the mass of the nucleus is unchanged.

For example, potassium isotope 40|19 K decays by emitting a β particle. So it forms a nucleus of the calcium isotope 40|20 Ca.

Question 21

🟠 What is Gamma (γ) Emission

Answer 21

A γ-ray is electromagnetic radiation from the nucleus of an atom. It is uncharged and has no mass. So its emission does not change the number of protons of neutrons in a nucleus. So the mass and the charge of the nucleus are both unchanged.

(Gamma – after α or β decay surplus energy is sometimes emitted. The atom itself is not changed.

Gamma radiation is part of the EM Spectrum; a wave with a very high frequency, very short wavelength.)

Question 22

🟠 What is Neutron Emission?

Answer 22

Neutrons are emitted by some radioactive substances as a result of α particles colliding with unstable nuclei in the susbtance. Such a collision causes the unstabke nuclei to become even more unstable and emit a neutron. Because the emitted neutrons are uncharged, they can pass through substances more easily than an α particle or a β particle can.

Question 23

🟠 Write an equation to show how Americium- 241 decays by alpha emission?

Answer 23

241|95 Am –> 237|93 Np + 4|2 α

Question 24

🟠 Write an equation to show how Carbon- 14 decays by beta emission?

Answer 24

14|6 C –> 14|7 N + 0|-1 β

Question 25

🟠 Which type of nuclear radiation is the most dangerous?

Answer 25

Alpha radiation is more dangerous in the body that beta or gamma radiation. This is because the ionising power of alpha radiation js much greater than the ionising power of beta or gamma radiation.

Workers who use ionising radiation reduce their exposure by:

• Keeping as far away as possible from the source of radiation (e.g by using special handling tools with long handles)
• Spending as little tine as possible in at-risk areas
• Shielding theselves by staying behind thick concrete barriers and/or using thick lead plates.

Question 26

🟠 Alpha Radiation Properties:

• Symbol
• Range In Air
• Stopped By
• Ionising Ability

Answer 26

Symbol:
α

Range In Air:
5cm

Stopped By:
Thin paper

Ionising Ability:
Very strongly ionising

Question 27

🟠 Beta Radiation Properties:

• Symbol
• Range In Air
• Stopped By
• Ionising Ability

Answer 27

Symbol:
β

Range In Air:
1m

Stopped By:
A few mm of aluminium

Ionising Ability:
Moderately ionising

Question 28

🟠 Gamma Radiation Properties:

• Symbol
• Range In Air
• Stopped By
• Ionising Ability

Answer 28

Symbol:
γ

Range In Air:
Unlimited

Stopped By:
A few cm of lead, or 1m thick concrete

Ionising Ability:
Weakly ionising

Question 29

🟠 What is Ionising Power

Answer 29

Ionising power is the ability for nuclear radiation to remove electrons from atoms to form ions.

Question 30

🟠 What type of Radiation is the most Ionising?

Answer 30

Alpha particles have the largest mass and charge, so they are the most ionising. Gamma rays do not interact with electrons trongly at all

Question 31

🟠 What is the ‘Peer Review’

Answer 31

Over the years, scientists have explored the effects of radiation on humans.

It is really important that these studies are published and then shared with other scientsists.

This allows the findings to be checked (peer reviewed)

Question 32

🟠 What is Ionisation?

Answer 32

The radiation from a radioactive substance can knock electrons out of atoms. The atoms become charged because they lose electrons. The process is called ionisation. When can object is exposed to ionising radiation, it is said to irradiated, but it does not become radioactive

Question 33

🟠 What does it mean if something is said to be Irradiated?

Answer 33

When can object is exposed to ionising radiation, it is said to irradiated, but it does not become radioactive.

Question 34

🟠 What is Radioactive Contamination?

Answer 34

Radioactive substances can contaminate other materials that they come into contact with. Radioactive contamination is the unwanted prescence of materials containing radioactive atoms on other materials. The hazard from contamination is due to the decay of the nuclei of the contaminating atoms. The type of radiation emitted affects the level of hazard.

Question 35

🟠 How are Alpha Particles used in Smoke Alarms?

Answer 35

Smoke alarms contain a radioactive isotope that semds out alpha particles into a gap in the circuit in the alarm. The alpha particles ionide the air in the gap so there is a current across the gap. In a fire, smoke absorbs the alpha particles, prevemting them from ionising the air, so the current across the gap drope and the alarm sounds.

Beta or gamma radiation could not be used because they do not create enough iond to make the air in the gap conduct electricity.

Question 36

🟠 How are Beta Particles used Automatic Thickness Monitoring in Metal Foils

Answer 36

Automatoc thickness monitoring in metal foil production uses a radioactive source that sends out β radiation. The amount of β radiation passing through the foil depends on the thickness of the foil. The detector measures the amount of radiation passing through the foil. If the foil is too thick, the detector reading drops and the detector sends a signal to imcrease the pressure of the rollers on the metal sheet. This makes the foil thinner again.

Gamma radiation isn’t used because it would all pass through the foil unaffected. Alpha radiation isn’t used as it would all be stopped by the foil.

Question 37

🟠 What would Carbon-14 change into after:

• Alpha Decay
• Beta Decay

Answer 37

• Beryllium-10

- Nitrogen-14

Question 38

🟠 Nuclear Equation for Alpha Decay? (“Element X”)

Answer 38

A|Z X —> 4|2 α + A-4|Z-2 X

Question 39

🟠 Nuclear Equation for Beta Decay?

Answer 39

A|Z X —> 0|-1 β + A|Z+1 X

Question 40

🟠 What is the Activity of a radioactive source?

Answer 40

The activity of a radioactive source is the number of unstable nuclei that decay every second

Units: Becquerels [Bq]

Question 41

🟠 What happens to the activity of a source as more and more unstable atoms decay?

Answer 41

The activity decreases as less atoms unstable atoms are able to decay (because they’ve already decayed and become stable).

Question 42

🟠 What is Count-rate?

Answer 42

Count-rate is the number of decays recorded each second by a detector (e.g Geiger-Muller Counter)

Question 43

🟠 What does a graph of ‘Count Rate’ against Time (‘minutes’) show?

Answer 43

The graph would should a line sloping down and then to the side.

This is because the activity decreases ofer time as less atoms unstable atoms are able to decay (because they’ve already decayed and become stable).

Question 44

🟠 What is Half-Life

Answer 44

Half-life is the time taken for half of the atoms in a sample to decay

(The average time taken for the count rate to fall by half.)

E.g Iodine-131 has a half-life of 8 days

Question 45

🟠 Explain why the number of dice that ‘decay’ decreases as the roll number increases

Answer 45

The activity decreases as less atoms unstable atoms are able to decay (because they’ve already decayed and become stable).

Question 46

🟠 Why is the dice model is a good model for radioactive decay?

Answer 46

• It shows the unpredictable nature of radioactive decay

- It shows that it is random

Question 47

🟠 How do you Calculate Half-Lives?

Answer 47

• If we know how many half lives have elapsed, how can we work out the value for our count-rate, activity, or remaining undecayed atoms

n = number of half-lives

Count Rate after n half-lives = Count Rate Before / 2^n

Question 48

🟠 Worked Example:

A particular radioisotope has a half life of 6.0 hours. A sample of this isotope contains 60,000 radioactive nuclei. Calculate the number of radioactive nuclei of this isotope remaining after 24 hours

Answer 48

n = 4 because 24 hours equals 4 half-lives for this isotope.

2^4 = 16, so the number of radioactive nuclei of the isotope remaining after 24 hours

=60,000 / 2^4 = 3750

Question 49

🟠 A sample of a radioactive isotope contains 320 million atoms of the isotope.

i) Calculate how many atoms of the isotope are present after one half-life
ii) Calculate the ratio of the number of atoms of the isotope left after five half lives to the intial number of atoms
iii) Calculate the number of atoms of the isotope left after five half-lives

Answer 49

i) 160 million atoms
ii) 320:1
iii) 1 million atoms

Question 50

🟠 Net Decline Definition

Answer 50

It’s how much the the count rate of a sample has decreased by after radioactive decay.

Question 51

🟠 How do you find the half life of the source on a graph

Answer 51

You look at the highest value for counts per second, and then half it.

You then go across from this number to where the line of best fit curve passes through, and the take the reading of the X coordinate that the line lies on.

That’s the half life.

Question 52

🟠 A sample of radioactive material emits 400 000 particles over a period of 20 minutes.

Calculate the activity of the source in Becquerel (Bq).

Answer 52

400,000/20 = 20,000
20,000/60 = 333.3

333.3 Bq

Question 53

🟠 The half-life of a source of carbon-14 is 5760 years. After how many years will the number of radioactive particles left be 12.5% of the original amount?

Show your working out here.

Answer 53

1 half-life, 50% = 1/2
2 half-life, 25% = 1/4
3 half-life, 12.5% = 1/8

1-7/8 = 1/8

5760/2^3 = 720 year

Question 54

🟠 The half-life of radon-222 is 3.8 days. If the original activity of this source was 2400 Bq, what do you expect it to be after 15.2 days?

Show your working out here.

Answer 54

15.2/3.8 = 4
(1/2)^4 = 1/16
2400 x 1/6 = 150

150Bq

Question 55

❌ Radioactive Tracers:

• What is it used for
• Describe how it works
• Explain why the radioactive substance is used

Answer 55

What is it used for:
- To check the flow of a substance through an organ (e.g the kidney)

Describe how it works:
- A very small amount of a radioactive isotope, e.g iodine, is ingested and detectors placed against each kidney. If the radiation through the rises and falls, the kidney isn’t blocked. If the radiation stays high, the iodine is stuck in the kidney.

Explain why the radioactive substance is used:
- Iodine emits gamma radiation, which is penetrative enough to leave the body and isn’t too harmful too. It also decays within a few weeks into a stable product (as it has a half life of around 8 days).

Question 56

❌ Gamma Cameras:

• What is it used for
• Describe how it works
• Explain why the radioactive substance is used

Answer 56

What is it used for:
- Gamma cameras are used to take images of internal body organs

Describe how it works:
- Before the image is taken, the patient is injected with a solution that absorbed by the organ, and a nearby ga,ma camera detects the gamma radiation emitted by the solution. The gamma eays pass through the holes in the thick lead grid in front if the detector. The detector only detects ga,ma rays from the nuclei directly in front of it. The detector signals are used to build up an image of where the radioactive isotope is located in the organ.

Explain why the radioactive substance is used:
- The radioactive isotope must be a gamma emitter with a half-life long enough to give a useful image, but short enough so that its nuclei have mostly decayed after the image has been taken.

Question 57

❌ Radioactive Tracers:

• What is it used for
• Describe how it works
• Explain why the radioactive substance is used

Answer 57

What is it used for:
- It’s used for destroying tumours

Describe how it works:
- A concentrated beam of gamma radiation is directed at the tumour to damage it. The radiation is emitted from a radioactive isotope of cobalt. Gamma radiation is used as it is more penetrative than Alpha or Beta radiation.

Explain why the radioactive substance is used:
- Cobalt has a half life of five years

Question 58

❌ Radioactive Implants:

• What is it used for
• Describe how it works
• Explain why the radioactive substance is used

Answer 58

What is it used for:
- Radioactive implants are used to destroy cancer cells in some tumours

Describe how it works:
- Beta or gamma emitting isotopes are used in the form of small seeds or tiny rods. Permanent implants use isotopes with half lives long enough to irradiate the tumour over a given time

Explain why the radioactive substance is used:
- Permanent implants use isotopes with half lives long enough to irradiate the tumour over a given time, but short enough so that most of the unstable nuclei will have decayer soon afterwards.

Question 59

❌ What are radioactive tracers used for?

Answer 59

Radioactive tracers are used to trace the flow of a substance through an organ. The tracer conatins a radioactive isotope that emits gamma radiation as it can be detected outside the system.

Question 60

❌ Give an example of a radioactive substance used as a tracer and explain why it is used

Answer 60

Iodine, because it emits gamma radiation which can be detetced and it has a short half life of 8 days, meaning it decays into a stable substance after a few weeks.

Question 61

❌ How can you tell there is a blockage in a kidney using a radioactive tracer

Answer 61

When a tracer has been injected into the kidney, if the reading/tracer goes up, and not back down, it shows the kidney is blocked as it can’t pass through

Question 62

❌ In gamma cameras explain why the radioactive isotope used in an organ scan has a half-life that is not too short and not too long

Answer 62

The radioactive isotope must be a gamma emitter with a half-life long enough to give a useful image, but short enough so that its nuclei have mostly decayed after the image has been taken.

Question 63

❌ Why is gamma radiation used to destroy cancer cells instead of alpha and beta radiation?

Answer 63

Gamma radiation is used because alpha and beta radiation isn’t penetrating enough, and beta radiation

Question 64

❌ It is great that radioactive substances can destroy cancer cells but what effect will it have on surrounding healthy cells?

Answer 64

It may damage/destroy surroundings and healthy cells, although it does destroy the targetted cancer cells.

Question 65

❌ What two thing can reduce the risks of radiation for patients

Answer 65

• Photographic films are used on X-rays

- Radiation badges can be used which have filters made from different materials

Question 66

❌ What is Nuclear Fission?

Answer 66

Nuclear fission is the spitting of a nucleus to form two smaller nuclei with the release of energy and two or three neutrons

Spontaneous fission is rare. Usually, for fission to occur the unstable nucleus must first absorb a neutron

Question 67

❌ What are atoms that can undergo nuclear fission?

Answer 67

Not all atoms can undergo nuclear fission.

Those that can are called fissionable.

Question 68

❌ Give an example of how Nuclear Fission works inside a Uranium- 235 atom

Answer 68

• Neutron is introduced to the Uranium - 235 nucleus
• The U- 236 nucleus is unstable by firing a neutron at it relatively slowly.
• The U- 236 splits to form 2 daughter nuclei and release/free neutrons. The daughter nucleuses will be Kryptonite- 92 and Barium- 141

Question 69

❌ How can Nuclear fission cause Chain Reactions

Answer 69

During fission, neutrons (fission product) fired from a nucleus have kinetic energy and can go onto cause further fission, resulting in a chain reaction.

Question 70

❌ Describe the purpose of fuel rods in a nuclear reactor

Answer 70

The control rods are put in to control the rate of the nuclear reactions by absorbing neutrons. These control rods are taken back out when the reaction is back at a steady rate.

Question 71

❌ If the control rods in a nuclear reactor are pushed further into the reactor core, what would happen to the number of fission neutrons in the reactor?

Answer 71

When the control rods are being pushed further into the reactor core they will absorb neutrons that are being fired around due to nuclear fission. This slows the rate of the neuclear reactions until they are at a steady rate. The rods are then lifted.

Question 72

❌ Explain why the core of a nuclear reactor is in a container made of thick steel surrounded by thick concrete walls?

Answer 72

It’s in a container of thick steel surrounded by the thick concrete walls. Thick steel will withstand very high temperatures and high pressure in the core reactor. The concrete wall absorbs any ionising radiation that escapes through the walls of the steel vessel.

Question 73

❌ Describe how the energy from nuclear fission is used to generate electricity

Answer 73

The energy used to generate electricity, is produced from the nuclear fission which produces heat. The heat produces high pressure steam, and this steam drives a turbine which then turns a generator.

Question 74

❌ Name two substances used as a fuel in some nuclear reactors

Answer 74

• Uranium

- Plutonium

Question 75

❌ What is Nuclear Fission

Answer 75

Nuclear fusion is the joining of two (lighter) atomic nuclei to form a larger one. This process releases energy

Question 76

❌ What does a Nucleus undergoes fission, what does it release?

Answer 76

It releases:

• Two or three neutrons (called fission neutrons) at high speeds
• Energy, in the form of gamma radiation, plus kinetic energy stored in the fission neutrons and fragment nuclei

Question 77

❌ What do Hydrogen- 1 and Hydrogen- 2 fuses together to form?

1|1H + 2|1 H —>

Answer 77

1|1H + 2|1 H —> (Atomic Nuclei Fuse Together) 3|2 He

Hydrogen- 1 nuclei fuse with hydrogen- 2 nuclei to make helium- 3 nuclei.

Question 78

❌ Complete the Nuclear Fission reaction equation:

1|1 H + 1|1 H —> _________

Answer 78

1|1 H + 1|1 H —> 3|1 H + 1|1 H (hydrogen without a neutron)

Question 79

❌ What are the technical difficulties with making Fusion a useful source of energy?

Answer 79

There are very big technical difficulties with making fusion a useful source of energy. The plasma of light nuclei has to be heated to very high temperatures and very high pressures before the nuclei will fuse.

This is because two nuclei approaching each other will repel each other because of their positive charges. But if the nuclei are moving fast enough, they can overcome this force of repulsion and fuse together.

In a fusion reactor:

• The plasma is heated by passing a very big electric current through it
• The plasma is contained by a magnetic field so that it doesn’t touch the reactor walls. If it did, it would go cold, and fusion would stop.

Question 80

❌ What is Background Radiation?

Answer 80

Background radiation is a measure of the level of ionising radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.

Background radiation originates from a variety of sources, both natural and artificial.

Question 81

❌ What is Background Radiation caused by? (+What does Radon do?)

Answer 81

Background radiation in the air is mostly caused by radon gas that seeps through the ground from radioactive substances in rocks deep underground.

Question 82

🟠 What type of Radiation does Radon emit and how can it be a hazard

Answer 82

Radon gas emits alpha particles, do radon is a health hazard if it is breathed in. It can seep into somes and other buildings in some locations. In affected home, pipes under the building can be installed and fitted to a suction pump to draw the gas out of the ground before it seeps into the building.

Question 83

🟠 What happens to Fuel Rods after they’re removed from a reactor?

Answer 83

Used fuel rods are very hot and radioactive. After they are removed from a reactor, they are stored in big tanks of water for up to a year. The water cools the rods down.

Remote-control machines are then used to open the fuel rods. The unused uranium and plutonium are removed chemically from the used fuel. These are stored in sealed containers so that they can be used again.

That material that’s left contains lots of radioactive isotopes with long half-lives. This radioactive waste has to be stored in secure conditions for many years to prevent radioactive contamination of the environment.

Question 84

🟠 What are two examples of Nuclear Reactors Going Wrong

Answer 84

• In 1986, a nuclear reacor in Chernobyl, Ukraine exploded, and a cloud of radioactive magerial from the fire drifted over many parts of Europe, including Britain. 30 people died in the accident, and many others developed leukemia orother types of cancer in the years since. (This happened from the Chernobyl operators ingnoring safety instructions)
• The nuclear plants in Fukushima were crippled in 2011, meaning the entire population with 20km were evacuated from their homes. Radiation levels, food, and milk production, and health effects over a much wider area will need to be monitored for many years

Question 85

🟠 What do new third-generation nuclear reactors have/do (What are their qualities)

Answer 85

Most nuclear reactors in use will need to replaced in the next 20 years with new third-generation nuclear reactors.

The new types of reactors could have:

• A standard design to reduce costs and construction time
• A longer operating life - typically 60 years
• More safety features, such as convection of outside air through cooling panels along the reactor walls
• Much less effect on the environment

Question 86

🟠 What does half life show you about a radioactive source

Answer 86

Isotopes with the shortest half-lives have the most unstable nuclei, so they emit lots of radiation in a short time.

The half-life of a radioactive source tells you quickly its activity decreases. As its activity decreases, the rate it gives out radiation decreases. So the hazards caused by the ionising effect of the radiation from radioactive materials decrease with time according to the half-lives of their isotopes.

Question 87

🟠 What risks do Radioactivity cause to the Human Body (+What Factors affect the risk)

Answer 87

The effect of radiation on living cells depends on the type and amount of radiation received (the dose), whether the source of radiation is inside or outside the body, and how long the living cells are exposed to the radiation. The bigger does of radiation someone gets, the higher the risk of cancer. High doses kill living cells.

Smaller does poss less risk but the risk is never zero. There is a very low level of risk to every perosn because of background radiation.

Question 88

🟠 Alpha Radiation Danger:

• Affect Outside of the Body
• Affect Inside of the Body

Answer 88

Inside the Body:

Very dangerous - It affects all of the surrounding tissue

Outside the Body:

Somewhat Dangerous - It is absorbed by the skin, it damages skin cells, and retinal cells.

Question 89

🟠 Beta and Gamma Radiation Danger:

• Affect Outside of the Body
• Affect Inside of the Body

Answer 89

Affect Everywhere in or out of the body:

(Moderately) Dangerous - They reach cells throughout the body

Question 90

🟠 What is the difference between irradiation and radioactive contamination?

Answer 90

When an object is exposed to ionising radiation, it is said to be irradiated, but it does not become radioactive, however, radioactive contamination is the unwanted presence of matrials that contains radioactobe atoms on other materials.

Question 91

🟠 What is radon gas and why is it dangerous?

Answer 91

Radon gas is a natural radioactive gas that comes from the decay of uranium of rocks, meaning it can come up from the ground as it’s a gas and go into buildings. It’s harmful as it can lead to lung cancer.

Question 92

❌ What are the most common sources of background radiation and are they harmful to us?

Answer 92

Background radiation can come from the ground, the air, and from cosmic rays from space. Radiation is harmful, as it can alter genetic codes in people’s cells, which can damage organs and tossue, and lead to other complications.

Question 93

🟠 Explain why radioactive material become less dangerous as times goes by (2 marks)

Answer 93

Radioactive material becomes less dangerous as time goes by, due to the atom’s half-lives. This means as time progesses, there are fewer and fewer atoms that decay

Question 94

🟠 Suggest two reasons why there is a ban on disposing of radioactive waste in the sea. (2 marks)

Answer 94

One reason that dumping radioactive waste in the sea is banned, it that it could contaminate the seas further, and could possibly lead to some water supplies being contaminated as well. Another reason is that it may also harmful marine wildlife.