P6 Flashcards
(106 cards)
1
Q
What is inside the nucleus of an atom?
A
Inside an atom’s nucleus are protons and neutrons, which are subatomic particles.
2
Q
What are the charges of protons, neutrons, and electrons?
A
Protons have a positive charge, electrons have a negative charge, and neutrons have no charge.
3
Q
What determines the charge on the nucleus of an atom?
A
The charge on the nucleus depends on the number of protons in it.
4
Q
What is an isotope?
A
Atoms of an element with different numbers of neutrons are called isotopes.
5
Q
How is an isotope represented?
A
Isotopes are written in the format ‘name-mass number’, e.g., carbon-12.
6
Q
What happens when you add a neutron to an atom of hydrogen?
A
You create an isotope called deuterium, or hydrogen-2.
7
Q
What is heavy water?
A
Deuterium oxide (D2O) is called ‘heavy water’.
8
Q
What is the difference between mass number and atomic number?
A
The mass number is the total number of subatomic particles in the nucleus, while the atomic number is the number of protons.
9
Q
How do you calculate the number of neutrons in an atom?
A
Subtract the atomic number from the mass number.
10
Q
What is the mass number of carbon-12?
A
The mass number of carbon-12 is 12.
11
Q
What is the atomic number of uranium?
A
The atomic number of uranium is 92.
12
Q
Why are isotopes written as ‘name-mass number’?
A
Isotopes are written this way to indicate the total number of subatomic particles, not just the atomic number.
13
Q
Why does heavy water not have twice the mass of normal water?
A
Heavy water contains deuterium, which has one neutron, while normal water contains protium, which has no neutrons.
14
Q
What are the types of radiation emitted by unstable nuclei?
A
Alpha, beta, and gamma radiation.
15
Q
What is the penetrating power of alpha radiation?
A
Alpha radiation can be stopped by a few sheets of paper or the outer layer of skin.
16
Q
What is the penetrating power of beta radiation?
A
Beta radiation can pass through paper but is stopped by aluminium.
17
Q
What is the penetrating power of gamma radiation?
A
Gamma radiation is the most penetrating and can pass through several centimeters of lead or meters of concrete.
18
Q
How do you detect radiation?
A
Radiation is detected with a Geiger-Müller tube, or Geiger counter, which clicks when radiation ionizes atoms of the gas inside.
19
Q
What is ionising radiation?
A
Ionising radiation is radiation that can remove electrons from atoms to produce positively charged ions.
20
Q
What is the relative mass and charge of alpha radiation?
A
Alpha radiation has a large relative mass and a charge of +2.
21
Q
What is the relative mass and charge of beta radiation?
A
Beta radiation has a small relative mass and a charge of -1.
22
Q
What is the relative mass and charge of gamma radiation?
A
Gamma radiation has no relative mass and no charge.
23
Q
What is the ionising power of alpha radiation?
A
Alpha radiation has high ionising power.
24
Q
What is the ionising power of beta radiation?
A
Beta radiation has medium ionising power.
25
What is the ionising power of gamma radiation?
Gamma radiation has low ionising power.
26
What happens when a neutron decays?
A neutron decays into a proton and an electron.
27
Who was the first person to use the word 'radioactive'?
Marie Curie.
28
What material could be used for lining containers that transport radioactive materials?
Lead or concrete.
29
What are the learning outcomes of the lesson on nuclear equations?
You should be able to describe particle changes in alpha, beta, and neutron decay, describe changes in mass and charge of a nucleus that emits radiation, and write balanced equations for nuclear decay.
30
What happens in alpha decay?
Large nuclei emit an alpha particle, which consists of two protons and two neutrons.
31
How is a nuclear decay equation balanced?
The total number of protons and neutrons before and after decay must be the same, ensuring mass and charge are conserved.
32
What happens in beta decay?
A neutron decays into a proton and an electron, with the electron emitted as a beta particle.
33
What is the nuclear equation for beta decay?
IC → IN + je
34
What happens in gamma decay?
Gamma rays are emitted without changing the atomic number or mass number of the nucleus.
35
What happens in neutron emission?
Some nuclei emit neutrons, producing a more stable nucleus without changing the element.
36
What is the nuclear equation for the beta decay of caesium-137?
137 Cs → 137 Ba +
## Footnote
Atomic number of caesium is 55, and the element with atomic number 56 is barium.
37
What is the nuclear equation for the alpha decay of uranium-238?
238 U → 234 Th + 4 He
38
How do alpha and beta decay compare in terms of mass and charge?
Alpha decay reduces mass and charge, while beta decay increases charge but keeps mass the same.
39
What is a study tip for checking nuclear decay equations?
Always check that the mass number total and atomic number total are the same before and after decay.
40
What is half-life?
The time it takes for the activity of a radioactive material to halve, which is the same as the time for half of the nuclei of the atoms to decay.
41
How is the activity of radioactive material measured?
Activity is measured in becquerels (Bq), which is one count (wave or particle) per second.
42
What does a Geiger counter measure?
A Geiger counter measures the radiation emitted per second, known as the activity or count rate.
43
What is the relationship between half-life and decay?
The probability that any one nucleus decays in one second is fixed, meaning decay is random and the half-life is constant.
44
What happens to radioactive atoms after decay?
After decay, radioactive atoms change to a different element and eventually become stable.
45
How do you calculate the ratio of final to initial activity using half-life?
The ratio of final to initial activity is known as the net decline. For example, after one half-life the ratio is 1:2; after two half-lives it is 1:4.
46
How do you calculate the number of half-lives?
Number of half-lives = total time / half-life duration.
47
What is the activity of a radon-222 sample after 11.4 days if its initial activity is 100 Bq?
After 11.4 days (3 half-lives), the activity is 12.5 Bq.
48
What is the half-life of carbon-14?
The half-life of carbon-14 is 5700 years.
49
What is the half-life of uranium-238?
The half-life of uranium-238 is 4.5 billion years.
50
What is the half-life of helium-6?
The half-life of helium-6 is 0.8 seconds.
51
What is the half-life of radon-222?
The half-life of radon-222 is 3.8 days.
52
How does the activity of a sample change over time?
The activity decreases over time, halving after each half-life.
53
What is the significance of the half-life in forensic science?
Forensic scientists can estimate the time of death using the level of carbon-14 in bones and its half-life.
54
What is the difference between contamination and irradiation?
Contamination occurs when radioactive material is taken inside the body or is on the skin, while irradiation happens when radioactive material is outside the body and the radiation travels into it.
55
How does half-life affect the hazard of radioactive material?
The half-life of a radioactive isotope determines how long it emits radiation. A short half-life means it decays quickly, while a long half-life increases the risk of cancer due to prolonged radiation exposure.
56
What is Technicium-99 used for in medicine?
Technicium-99 is a radioisotope absorbed by various organs and is used as a tracer in medical imaging due to its half-life of just over 6 hours.
57
How are nuclear radiations used in cancer treatment?
Gamma rays emitted from radioactive materials can damage or kill cancer cells. A moveable source of gamma radiation, known as a gamma knife, is used to focus the radiation on a tumor.
58
Why do doctors choose tracers that emit gamma radiation?
Doctors prefer gamma emitters because they penetrate tissues better than alpha or beta emitters, allowing for clearer imaging and diagnosis.
59
Why is the risk of cancer usually higher with contamination than irradiation?
Contamination leads to radioactive material being inside the body, which can continuously emit radiation and damage DNA, increasing cancer risk.
60
What precautions do radiochemists take when preparing radioactive tracers?
Radiochemists take precautions to reduce the chance of contamination or irradiation during the preparation of radioactive tracers.
61
What is a gamma knife?
A gamma knife is a medical device that uses a moveable source of gamma radiation to treat tumors while minimizing radiation exposure to healthy tissue.
62
What happens when you are irradiated?
When you are irradiated, you do not become radioactive; you only become radioactive if you are contaminated.
63
What is nuclear fission?
Nuclear fission is the process where a large nucleus splits into fragments and emits neutrons, producing two smaller nuclei.
## Footnote
Fission is more likely to occur when a nucleus absorbs a neutron.
64
What types of nuclei can undergo nuclear fission?
The nuclei of uranium-235 and uranium-239 are fissionable, meaning they can be split easily.
65
What is a chain reaction?
A chain reaction occurs when neutrons produced from one fission reaction trigger additional fission reactions, leading to billions of fissions per second in a nuclear power station.
66
What is meant by 'critical mass'?
Critical mass refers to the minimum amount of radioactive material needed to sustain a chain reaction.
67
How is a chain reaction controlled in a nuclear power station?
In a nuclear power station, engineers control the chain reaction by using materials that absorb some of the neutrons.
68
What happens in a nuclear bomb compared to a nuclear reactor?
In a nuclear bomb, there is no absorption of neutrons and no control of fission, resulting in a rapid release of a huge amount of energy.
69
What is the energy output of 1 kg of nuclear fuel compared to coal?
1 kg of nuclear fuel produces the same amount of energy as 30,000 tonnes of coal.
70
Why is fission different from alpha or beta decay?
Fission refers to splitting a large nucleus, while alpha and beta decay are forms of radioactive decay.
71
What is the significance of nuclear weapons?
Nuclear weapons have a significant impact on society due to their immense destructive power and the threat they pose.
72
What is nuclear fusion?
Nuclear fusion is the process where lighter nuclei join together to make more stable nuclei, releasing large amounts of energy.
73
What happens in nuclear fusion?
In nuclear fusion, two small nuclei combine to form a larger nucleus, releasing energy in the process.
74
What are the conditions necessary for nuclear fusion to occur?
High temperatures and high pressures are necessary for nuclear fusion to occur, allowing nuclei to move at high speeds and stay close enough to fuse.
75
What is the significance of the equation E = Δmc² in nuclear fusion?
The equation E = Δmc² relates the change in mass (Δm) to the energy (E) produced in a fusion reaction, indicating that a small amount of mass can produce a large amount of energy.
76
What elements can be produced through nuclear fusion?
Nuclear fusion can produce elements such as helium, carbon, and oxygen, but cannot create elements heavier than iron.
77
Why is it difficult to achieve nuclear fusion on Earth?
It is difficult to reproduce the high temperatures and pressures necessary for nuclear fusion on Earth.
78
What is a positron?
A positron is a particle produced when hydrogen fuses to make deuterium.
79
What do scientists believe about the creation of elements heavier than iron?
Scientists believe that elements heavier than iron were created in supernovae, or exploding stars.
80
What is the relationship between mass and energy as proposed by Einstein?
Einstein's equation E = Δmc² shows that mass can be converted into energy, explaining the energy produced in nuclear reactions.
81
What happens to electrons in atoms?
Electrons can be excited and move up energy levels, then move down energy levels.
82
What is electromagnetic radiation?
Electromagnetic radiation is composed of photons.
83
What does an absorption spectrum look like?
An absorption spectrum shows black lines.
84
What is an example of an absorption spectrum?
The hydrogen absorption spectrum ranges from 400 nm to 700 nm.
85
What does an emission spectrum look like?
An emission spectrum shows colored lines.
86
What is an example of an emission spectrum?
The hydrogen emission spectrum ranges from 400 nm to 700 nm.
87
What is half-life?
Half-life is the time over which the activity of a source decreases.
88
How does the activity ratio change over half-lives?
The ratio of final to initial activity can be represented as: 1:1 → 1:2 → 1:4 → 1:8.
89
What are isotopes?
Isotopes have different numbers of neutrons but the same proton number.
90
What is radiation?
Radiation consists of particles or waves emitted from unstable nuclei.
91
What are the types of radiation?
The types of radiation are alpha (α), beta (β), and gamma (γ).
92
What is the charge and penetrating power of alpha radiation?
Alpha radiation has a charge of +2 and is stopped by paper.
93
What is the charge and penetrating power of beta radiation?
Beta radiation has a charge of -1 and can penetrate a couple of cm.
94
What is the charge and penetrating power of gamma radiation?
Gamma radiation has no charge and can penetrate several cm of lead.
95
What is the impact of ionising radiation?
Ionising radiation damages living cells, which can lead to cancer.
96
What is alpha decay?
Alpha decay is represented as: 219 Rn → 84 + α.
97
What is beta decay?
Beta decay is represented as: β + (change in neutron number).
98
What happens during gamma decay?
Gamma decay results in no change to the type of element; an excited nucleus releases energy.
99
What is nuclear fission?
Nuclear fission involves a neutron hitting a nucleus, resulting in two smaller nuclei and can cause a chain reaction.
100
How is electricity generated in a nuclear power station?
Electricity is generated using the equation E = Amc.
101
What are the main sources of background radiation?
Background radiation mainly comes from natural sources like rocks, radon, and cosmic rays.
102
What precautions are taken for medical uses of isotopes?
Isotopes with short half-lives are chosen for medical purposes, and protective clothing/screens are used for medical staff.
103
What is irradiation?
Irradiation refers to exposure from an external source.
104
What is contamination?
Contamination occurs when radioactive material is inside or on the body, and is usually more hazardous.
105
What is nuclear fusion?
Nuclear fusion involves two small nuclei combining to form one larger nucleus, releasing energy using E = Amc.
106
Is fusion power currently possible?
A fusion power station is not currently possible.
