Define energy level .

An energy level is a fixed region around the nucleus where electrons are found. Lower energy levels are closer to the nucleus; higher energy levels are further away.

What happens to an electron when it absorbs electromagnetic radiation?

When an electron absorbs electromagnetic radiation, it moves to a higher energy level , further from the nucleus.

True or False? When an electron moves to a higher energy level, it becomes more stable.

False. Moving to a higher energy level makes the electron unstable . It will eventually fall back down to its original energy level.

What is emitted when an electron moves down to a lower energy level?

A wave of electromagnetic radiation is emitted as the electron falls to a lower energy level.

A larger energy jump produces electromagnetic radiation with a .......... frequency.

A larger energy jump produces electromagnetic radiation with a higher frequency.

True or False? All colours in the visible spectrum are produced by electrons moving down energy levels and emitting electromagnetic radiation.

True. Every colour in the visible spectrum is produced when electrons move to a lower energy level and emit electromagnetic radiation of a characteristic frequency.

Why do different elements emit radiation at different frequencies?

Different elements have different energy level spacings, so electrons make different-sized energy jumps, producing radiation at characteristic frequencies .

In which region of the electromagnetic spectrum does neon emit light?

Neon emits light in the visible region of the electromagnetic spectrum.

Alpha decay is when an unstable nucleus emits an alpha particle , forming a new element. The mass number decreases by 4 and the atomic number decreases by 2 .

What is an alpha particle ?

An alpha particle is identical to a helium nucleus — it consists of 2 protons and 2 neutrons, giving it a charge of +2.

True or False? During alpha decay, the mass number of the nucleus decreases by 2.

False. During alpha decay , the mass number decreases by 4 (because an alpha particle contains 2 protons and 2 neutrons). The atomic number decreases by 2.

During alpha decay , how does the atomic number of the nucleus change?

The atomic number decreases by 2 , because the emitted alpha particle carries away 2 protons.

In a decay equation , the .......... number and the .......... number must each balance on both sides.

In a decay equation , the mass number and the atomic number must each balance on both sides.

Why does alpha decay always produce a completely new element?

Alpha decay removes 2 protons from the nucleus, changing the atomic number . Since the atomic number defines the element, a new element is always formed.

True or False? An alpha particle can be represented by the same symbol as a helium nucleus.

True. An alpha particle is identical to a helium nucleus and can be written as He in decay equations. The two terms are fully interchangeable .

A nucleus undergoes alpha decay . Its original mass number is 220 and atomic number is 86. What are the mass number and atomic number of the daughter nucleus?

Mass number: 220 − 4 = 216 Atomic number: 86 − 2 = 84

Beta decay occurs when a neutron in an unstable nucleus changes into a proton and a beta particle (high-speed electron) is emitted. The mass number stays the same; the atomic number increases by 1.

In beta decay , what change occurs inside the nucleus?

A neutron changes into a proton . The proton remains in the nucleus, and an electron (the beta particle ) is emitted.

True or False? During beta decay, the mass number of the nucleus increases by 1.

False. In beta decay , the mass number stays the same because a neutron (mass 1) is converted into a proton (mass 1). Only the atomic number increases by 1.

What is emitted from the nucleus during gamma decay ?

A gamma ray (electromagnetic radiation) is emitted. It carries energy but has no mass or charge.

True or False? Gamma decay does not change the atomic number or mass number of the nucleus.

True. Gamma decay only releases energy as a gamma ray . The mass number and atomic number of the nucleus are unchanged.

During beta decay, the atomic number .......... by 1, but the mass number remains the .......... .

During beta decay, the atomic number increases by 1, but the mass number remains the same .

What happens to the atomic number when a nucleus emits a neutron?

The atomic number stays the same. Neutron emission reduces the mass number by 1 but does not affect the number of protons.

A gamma ray is a high-energy electromagnetic wave emitted from an unstable nucleus during gamma decay. It has no mass and no charge.

Define radioactive decay .

Radioactive decay is the random emission of radiation from an unstable nucleus . It is random — it is impossible to predict which nucleus will decay next or when.

True or False? Radioactive decay is a predictable process: scientists can calculate exactly when a specific nucleus will decay.

False. Radioactive decay is random . It is impossible to predict when a particular nucleus will decay. Only the probability of decay in a given time can be estimated.

Half-life is the time for the number of radioactive nuclei in a sample to halve, or the time for the count rate (or activity) of a sample to fall to half its initial level.

How does the half-life of a radioactive isotope change over time?

The half-life stays constant for a given isotope — it does not change as the sample decays.

After two half-lives , the activity of a radioactive sample falls to .......... of its original value.

After two half-lives , the activity of a radioactive sample falls to one quarter (25%) of its original value.

A radioactive sample has an initial activity of 800 Bq. After three half-lives , what is the activity?

After three half-lives: 800 → 400 → 200 → 100 Bq .

True or False? A Geiger-Muller tube can be used to detect radioactive decay and provide evidence for its random nature.

True. A Geiger-Muller (GM) tube records counts that are irregular and unpredictable , providing evidence for the random nature of radioactive decay.

A sample contains 2 000 000 atoms. After one year, 500 000 atoms remain undecayed. What is the half-life ?

2 000 000 → 1 000 000 (1 half-life) → 500 000 (2 half-lives). Two half-lives = one year, so the half-life is 6 months .

After four half-lives, the fraction of original nuclei remaining is .......... . (Higher Tier Only)

After four half-lives, the fraction of original nuclei remaining is 1/16 . Each half-life halves the fraction remaining: 1/2 × 1/2 × 1/2 × 1/2 = 1/16.

A sample has a half-life of three years. What is the ratio of decayed to remaining nuclei after 15 years? (Higher Tier Only)

15 ÷ 3 = 5 half-lives . Remaining fraction = (1/2) 5 = 1/32. So 31/32 have decayed: ratio is 31:1 (decayed : remaining).

Define alpha particle .

An alpha particle consists of 2 protons and 2 neutrons (identical to a helium nucleus). It has a charge of +2 , travels only a few centimetres in air and is stopped by paper .

Which type of nuclear radiation has the highest ionising power ?

Alpha radiation has the highest ionising power. Its large mass and charge cause it to interact strongly with atoms it passes through.

True or False? Beta particles are stopped by a few millimetres of aluminium.

True. Beta particles are stopped by a few millimetres of aluminium . Thinner aluminium will not stop them — thickness matters.

What is the charge of a beta particle?

A beta particle has a charge of −1 . It is a high-speed electron ejected from the nucleus when a neutron changes into a proton.

Complete the table. Radiation Stopped by Range in air Alpha Beta Gamma

Radiation Stopped by Range in air Alpha Paper Few cm Beta Few mm of aluminium Few metres Gamma Thick lead / several metres of concrete Infinite

True or False? Gamma radiation is the most dangerous type of nuclear radiation because it is the most penetrating.

False. Danger depends on context . Gamma is the least ionising type of radiation, so in many situations alpha radiation (the most ionising) is more harmful — especially if inhaled or ingested.

What type of nuclear radiation has no charge and can travel infinite distances in air?

Gamma radiation. It is an electromagnetic wave with no charge, so it is not stopped by air and has an effectively infinite range.

Define ionising power .

Ionising power is the ability of radiation to remove electrons from atoms it passes through, creating ions . Alpha has the highest ionising power; gamma has the lowest .

A student places paper in front of a radioactive source and finds the count rate barely changes. What does this tell them about the radiation?

The radiation passes through paper , so it is not alpha . Alpha is the only type stopped by paper. The source likely emits beta or gamma radiation.

Define radioactive contamination .

Radioactive contamination is the unwanted presence of materials containing radioactive atoms on other materials. The hazard comes from the decay of those contaminating atoms.

What is the source of hazard in radioactive contamination?

The hazard comes from the decay of the contaminating radioactive atoms, which continuously emit radiation into the surrounding material.

True or False? An object that has been irradiated becomes radioactive.

False. Irradiation exposes an object to nuclear radiation, but the object does not become radioactive — no radioactive atoms are deposited onto it.

Irradiation is the process of exposing an object to nuclear radiation . The irradiated object does not become radioactive.

True or False? Irradiation can be used to sterilise surgical equipment by killing micro-organisms.

True. Irradiation can kill micro-organisms on surgical equipment. It is also used on food to extend shelf life, because it kills bacteria without making the food radioactive .

Contamination relates to the presence of a radioactive .......... , whereas irradiation relates to exposure to nuclear .......... .

Contamination relates to the presence of a radioactive substance , whereas irradiation relates to exposure to nuclear radiation .

How can the risk from irradiation be reduced?

The risk from irradiation can be reduced by screening the source (e.g. using lead shielding) or increasing the distance from the source.

True or False? Contamination and irradiation both result in the exposed object becoming permanently radioactive.

False. Irradiation does not make an object radioactive . With contamination , radioactive atoms are present on the material — but the object itself only becomes hazardous due to the ongoing decay of those deposited atoms.

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Radiation & Risk (AQA GCSE Combined Science: Synergy: Life & Environmental Sciences): Flashcards

Exam code: 8465

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FrontAbsorption & Emission Of Radiation
Define energy level.

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Cards in this collection (71)

Define energy level.
An energy level is a fixed region around the nucleus where electrons are found. Lower energy levels are closer to the nucleus; higher energy levels are further away.
What happens to an electron when it absorbs electromagnetic radiation?
When an electron absorbs electromagnetic radiation, it moves to a higher energy level, further from the nucleus.
True or False?
When an electron moves to a higher energy level, it becomes more stable.
False.
Moving to a higher energy level makes the electron unstable. It will eventually fall back down to its original energy level.
What is emitted when an electron moves down to a lower energy level?
A wave of electromagnetic radiation is emitted as the electron falls to a lower energy level.
A larger energy jump produces electromagnetic radiation with a .......... frequency.
A larger energy jump produces electromagnetic radiation with a higher frequency.
True or False?
All colours in the visible spectrum are produced by electrons moving down energy levels and emitting electromagnetic radiation.
True.
Every colour in the visible spectrum is produced when electrons move to a lower energy level and emit electromagnetic radiation of a characteristic frequency.
Why do different elements emit radiation at different frequencies?
Different elements have different energy level spacings, so electrons make different-sized energy jumps, producing radiation at characteristic frequencies.
In which region of the electromagnetic spectrum does neon emit light?
Neon emits light in the visible region of the electromagnetic spectrum.
Define alpha decay.
Alpha decay is when an unstable nucleus emits an alpha particle, forming a new element. The mass number decreases by 4 and the atomic number decreases by 2.
What is an alpha particle?
An alpha particle is identical to a helium nucleus — it consists of 2 protons and 2 neutrons, giving it a charge of +2.
True or False?
During alpha decay, the mass number of the nucleus decreases by 2.
False.
During alpha decay, the mass number decreases by 4 (because an alpha particle contains 2 protons and 2 neutrons). The atomic number decreases by 2.
During alpha decay, how does the atomic number of the nucleus change?
The atomic number decreases by 2, because the emitted alpha particle carries away 2 protons.
In a decay equation, the .......... number and the .......... number must each balance on both sides.
In a decay equation, the mass number and the atomic number must each balance on both sides.
Why does alpha decay always produce a completely new element?
Alpha decay removes 2 protons from the nucleus, changing the atomic number. Since the atomic number defines the element, a new element is always formed.
True or False?
An alpha particle can be represented by the same symbol as a helium nucleus.
True.
An alpha particle is identical to a helium nucleus and can be written as He in decay equations. The two terms are fully interchangeable.
A nucleus undergoes alpha decay. Its original mass number is 220 and atomic number is 86. What are the mass number and atomic number of the daughter nucleus?
1. Mass number: 220 − 4 = 216
2. Atomic number: 86 − 2 = 84
Define beta decay.
Beta decay occurs when a neutron in an unstable nucleus changes into a proton and a beta particle (high-speed electron) is emitted. The mass number stays the same; the atomic number increases by 1.
In beta decay, what change occurs inside the nucleus?
A neutron changes into a proton. The proton remains in the nucleus, and an electron (the beta particle) is emitted.
True or False?
During beta decay, the mass number of the nucleus increases by 1.
False.
In beta decay, the mass number stays the same because a neutron (mass 1) is converted into a proton (mass 1). Only the atomic number increases by 1.
What is emitted from the nucleus during gamma decay?
A gamma ray (electromagnetic radiation) is emitted. It carries energy but has no mass or charge.
True or False?
Gamma decay does not change the atomic number or mass number of the nucleus.
True.
Gamma decay only releases energy as a gamma ray. The mass number and atomic number of the nucleus are unchanged.
During beta decay, the atomic number .......... by 1, but the mass number remains the .......... .
During beta decay, the atomic number increases by 1, but the mass number remains the same.
What happens to the atomic number when a nucleus emits a neutron?
The atomic number stays the same. Neutron emission reduces the mass number by 1 but does not affect the number of protons.
In a beta decay equation, what symbol is used for the emitted particle?
The beta particle is written as an electron:
${}_{- 1}^{0}e$
Its atomic number is −1 and its mass number is 0.
Define gamma ray.
A gamma ray is a high-energy electromagnetic wave emitted from an unstable nucleus during gamma decay. It has no mass and no charge.
Define radioactive decay.
Radioactive decay is the random emission of radiation from an unstable nucleus. It is random — it is impossible to predict which nucleus will decay next or when.
True or False?
Radioactive decay is a predictable process: scientists can calculate exactly when a specific nucleus will decay.
False.
Radioactive decay is random. It is impossible to predict when a particular nucleus will decay. Only the probability of decay in a given time can be estimated.
Define half-life.
Half-life is the time for the number of radioactive nuclei in a sample to halve, or the time for the count rate (or activity) of a sample to fall to half its initial level.
How does the half-life of a radioactive isotope change over time?
The half-life stays constant for a given isotope — it does not change as the sample decays.
After two half-lives, the activity of a radioactive sample falls to .......... of its original value.
After two half-lives, the activity of a radioactive sample falls to one quarter (25%) of its original value.
A radioactive sample has an initial activity of 800 Bq. After three half-lives, what is the activity?
After three half-lives: 800 → 400 → 200 → 100 Bq.
True or False?
A Geiger-Muller tube can be used to detect radioactive decay and provide evidence for its random nature.
True.
A Geiger-Muller (GM) tube records counts that are irregular and unpredictable, providing evidence for the random nature of radioactive decay.
A sample contains 2 000 000 atoms. After one year, 500 000 atoms remain undecayed. What is the half-life?
2 000 000 → 1 000 000 (1 half-life) → 500 000 (2 half-lives). Two half-lives = one year, so the half-life is 6 months.
After four half-lives, the fraction of original nuclei remaining is .......... .
(Higher Tier Only)
After four half-lives, the fraction of original nuclei remaining is 1/16. Each half-life halves the fraction remaining: 1/2 × 1/2 × 1/2 × 1/2 = 1/16.
A sample has a half-life of three years. What is the ratio of decayed to remaining nuclei after 15 years?
(Higher Tier Only)
15 ÷ 3 = 5 half-lives. Remaining fraction = (1/2)⁵ = 1/32. So 31/32 have decayed: ratio is 31:1 (decayed : remaining).
Define alpha particle.
An alpha particle consists of 2 protons and 2 neutrons (identical to a helium nucleus). It has a charge of +2, travels only a few centimetres in air and is stopped by paper.
Which type of nuclear radiation has the highest ionising power?
Alpha radiation has the highest ionising power. Its large mass and charge cause it to interact strongly with atoms it passes through.
True or False?
Beta particles are stopped by a few millimetres of aluminium.
True.
Beta particles are stopped by a few millimetres of aluminium. Thinner aluminium will not stop them — thickness matters.
What is the charge of a beta particle?
A beta particle has a charge of −1. It is a high-speed electron ejected from the nucleus when a neutron changes into a proton.
Complete the table.
Radiation
Stopped by
Range in air
Alpha
Beta
Gamma
Radiation
Stopped by
Range in air
Alpha
Paper
Few cm
Beta
Few mm of aluminium
Few metres
Gamma
Thick lead / several metres of concrete
Infinite
True or False?
Gamma radiation is the most dangerous type of nuclear radiation because it is the most penetrating.
False.
Danger depends on context. Gamma is the least ionising type of radiation, so in many situations alpha radiation (the most ionising) is more harmful — especially if inhaled or ingested.
What type of nuclear radiation has no charge and can travel infinite distances in air?
Gamma radiation. It is an electromagnetic wave with no charge, so it is not stopped by air and has an effectively infinite range.
Define ionising power.
Ionising power is the ability of radiation to remove electrons from atoms it passes through, creating ions. Alpha has the highest ionising power; gamma has the lowest.
A student places paper in front of a radioactive source and finds the count rate barely changes. What does this tell them about the radiation?
The radiation passes through paper, so it is not alpha. Alpha is the only type stopped by paper. The source likely emits beta or gamma radiation.
Define radioactive contamination.
Radioactive contamination is the unwanted presence of materials containing radioactive atoms on other materials. The hazard comes from the decay of those contaminating atoms.
What is the source of hazard in radioactive contamination?
The hazard comes from the decay of the contaminating radioactive atoms, which continuously emit radiation into the surrounding material.
True or False?
An object that has been irradiated becomes radioactive.
False.
Irradiation exposes an object to nuclear radiation, but the object does not become radioactive — no radioactive atoms are deposited onto it.
Define irradiation.
Irradiation is the process of exposing an object to nuclear radiation. The irradiated object does not become radioactive.
True or False?
Irradiation can be used to sterilise surgical equipment by killing micro-organisms.
True.
Irradiation can kill micro-organisms on surgical equipment. It is also used on food to extend shelf life, because it kills bacteria without making the food radioactive.
Contamination relates to the presence of a radioactive .......... , whereas irradiation relates to exposure to nuclear .......... .
Contamination relates to the presence of a radioactive substance, whereas irradiation relates to exposure to nuclear radiation.
How can the risk from irradiation be reduced?
The risk from irradiation can be reduced by screening the source (e.g. using lead shielding) or increasing the distance from the source.
True or False?
Contamination and irradiation both result in the exposed object becoming permanently radioactive.
False.
Irradiation does not make an object radioactive. With contamination, radioactive atoms are present on the material — but the object itself only becomes hazardous due to the ongoing decay of those deposited atoms.
A scientist accidentally ingests a small amount of a radioactive substance. Is this an example of contamination or irradiation?
This is contamination. A radioactive substance is now present inside the body where it should not be, and it will continue to emit radiation as it decays.
Define ionising radiation.
Ionising radiation is radiation that has enough energy to remove outer electrons from atoms, turning them into charged particles called ions.
When ionising radiation passes close to an atom, it can knock out .......... , creating a charged particle called an .......... .
When ionising radiation passes close to an atom, it can knock out electrons, creating a charged particle called an ion.
Which type of ionising radiation is the most ionising?
Alpha radiation is the most ionising. It carries a charge of +2, which strongly attracts electrons from nearby atoms.
True or False?
Gamma radiation is the most ionising type of radiation.
False.
Gamma radiation is the least ionising because it has no charge, so it interacts less readily with matter. Alpha radiation is the most ionising.
What is the range in air of alpha radiation?
Alpha radiation only travels a few centimetres in air. Because it is strongly ionising, it loses energy quickly and has the shortest range in air.
True or False?
The more ionising a type of radiation is, the shorter its range in air.
True.
Strongly ionising radiation reacts with air molecules quickly, losing energy sooner. This gives alpha the shortest range (a few cm) and gamma an effectively infinite range.
What is radiation dose?
Radiation dose is a measure of the risk of harm from exposure to radiation. It is measured in Sieverts (Sv), where 1 Sv = 1000 millisieverts (mSv).
Alpha radiation is the most ionising, beta radiation is moderately ionising, and .......... radiation is the least ionising because it carries no .......... .
Alpha radiation is the most ionising, beta radiation is moderately ionising, and gamma radiation is the least ionising because it carries no charge.
State five types of ionising radiation.
The five types of ionising radiation are:
1. Ultraviolet (UV) waves
2. X-rays
3. Alpha particles
4. Beta particles
5. Gamma rays
How does ionising radiation damage the cells in human tissue?
Ionising radiation turns atoms into ions and breaks up molecules. This can cause changes to DNA, which may mutate genes and lead to cancer.
True or False?
A malignant tumour is contained in one area and does not spread to other parts of the body.
False.
A malignant tumour invades neighbouring tissues and can spread through the blood to form secondary tumours. It is benign tumours that are contained within one area.
What is a benign tumour?
A benign tumour is a tumour that is contained in one area, usually within a membrane. It does not invade other tissues or spread to different parts of the body.
Ionising radiation can cause changes to .......... in cells, which may lead to mutation of genes and ultimately to .......... .
Ionising radiation can cause changes to DNA in cells, which may lead to mutation of genes and ultimately to cancer.
State four hazardous effects of UV radiation on the human body.
UV radiation can cause:
1. Skin cancer
2. Sunburn and blistering
3. Damage to eyes (including cataracts)
4. Premature skin ageing
True or False?
Radiation workers wear dosimeters to monitor their total exposure to ionising radiation.
True.
Dosimeters are worn by radiation workers to track cumulative exposure. This helps ensure their total dose stays within safe limits.
When handling radioactive sources, sources should be held with .......... and lead shielding should be used to .......... radiation.
When handling radioactive sources, sources should be held with tongs and lead shielding should be used to absorb radiation.
What is cancer?
Cancer is caused by changes in the DNA of cells that lead to uncontrolled growth and division. Tumours form when cells divide without normal controls.
Why is alpha radiation particularly dangerous when a source is inhaled or ingested?
Alpha radiation is highly ionising. Inside the body it can cause severe damage to internal organs because it cannot be shielded by skin, making it far more dangerous internally than externally.

Radiation	Stopped by	Range in air
Alpha	Paper	Few cm
Beta	Few mm of aluminium	Few metres
Gamma	Thick lead / several metres of concrete	Infinite

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