Explain why an isotope with a very long half-life can be hazardous.

It decays slowly, so it stays radioactive and remains a hazard for a very long time.

Explain why an isotope with a very short half-life can be hazardous.

It decays quickly, so its activity is very high and it delivers a large dose in a short time.

Explain why a short half-life is an advantage for an isotope given to a patient.

Its activity falls away quickly, so the patient is exposed for only a short time before almost all of it has decayed.

Explain why nuclear waste containing long half-life isotopes is difficult to deal with.

It stays dangerously radioactive for thousands of years, so it must be stored securely for an extremely long time.

AQA GCSE Physics 8463

Atomic Structure

Topic overview The structure of an atom Mass number, atomic number and isotopes From the plum pudding model to the nuclear model Chadwick, the neutron, and comparing the models Radioactive decay and nuclear radiation Nuclear equations Half-lives and the random nature of radioactive decay Radioactive contamination Background radiation Uses of nuclear radiation, and how half-life affects hazard Nuclear fission and nuclear fusion

Electricity

Topic overview Circuit symbols, electrical charge and current Current, resistance and potential difference Ohmic conductors, filament lamps, diodes and thermistors Light-dependent resistors, and investigating resistance Current and potential difference in series and parallel Constructing circuits, and calculating in series circuits Direct and alternating potential difference, and mains electricity Power and efficiency Appliances, and the energy transferred by electrical work Power, and the power ratings of domestic appliances The National Grid Static charge Electric fields

Energy

Topic overview Energy stores and systems Kinetic energy Elastic and gravitational potential energy Energy changes in systems Power Energy transfers in a system The main energy resources, renewable and non-renewable Environmental impact and trends in energy use

Forces

Topic overview Scalars, vectors, forces and the resultant force Gravity Work done and energy transfer Stretching, compressing, and the spring constant Linear and non-linear extension, and work done on a spring Moments, levers and gears Pressure at a surface, and the equation p = F over A Atmospheric pressure Distance, displacement and speed The speed of sound, and the distance-speed-time equation Velocity and the distance-time relationship Acceleration, deceleration and velocity-time graphs Area under a velocity-time graph, and the uniform acceleration equation Newton's First Law Newton's Second and Third Laws Stopping distance and reaction time Factors affecting braking distance Braking force, deceleration and the dangers of stopping quickly

Magnetism and Electromagnetism

Topic overview Poles of a magnet Magnetic fields around a magnet The compass, and plotting a magnetic field Electromagnetism

Particle Model of Matter

Topic overview Density of materials Changes of state and internal energy Temperature changes in a system and specific heat capacity Changes of state and specific latent heat Particle motion in gases Pressure in gases, volume and temperature

Space Physics

Topic overview Our solar system, and the orbits of satellites The life cycle of a star Red-shift

Waves

Topic overview Transverse and longitudinal waves, and the wave equation Wave properties, and refraction at a boundary Reflection of waves Types and uses of electromagnetic waves Radio waves, and the hazards of ultraviolet, X-rays and gamma rays Lenses Visible light Emission and absorption of infrared radiation, and black bodies

Atomic Structure

Uses of nuclear radiation, and how half-life affects hazard

3 things to know
Paper 1

Overview

How widely half-lives vary and why very long and very short half-lives can each be hazardous, the problem of long-lived nuclear waste, medical tracers and the choice of isotope for them, treating tumours from several directions, evaluating radiation used to destroy tissue, and how the risk of medical radiation is perceived and judged.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Describe how nuclear radiation is used in medicine, both to explore an organ and to treat a tumour.

Key term

How widely do the half-lives of radioactive isotopes vary?

Key term

State two ways in which nuclear radiation is used in medicine.

Questions from this subtopic

Each one with the model answer underneath.

1
How widely do the half-lives of radioactive isotopes vary?
Model answer
Enormously, from fractions of a second up to many thousands of years.
2
Explain why an isotope with a very long half-life can be hazardous.
Model answer
It decays slowly, so it stays radioactive and remains a hazard for a very long time.
3
Explain why an isotope with a very short half-life can be hazardous.
Model answer
It decays quickly, so its activity is very high and it delivers a large dose in a short time.
4
Explain why a short half-life is an advantage for an isotope given to a patient.
Model answer
Its activity falls away quickly, so the patient is exposed for only a short time before almost all of it has decayed.
5
Explain why nuclear waste containing long half-life isotopes is difficult to deal with.
Model answer
It stays dangerously radioactive for thousands of years, so it must be stored securely for an extremely long time.
6
State two ways in which nuclear radiation is used in medicine.
Model answer
To explore how internal organs are working, and to control or destroy unwanted tissue.

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