Radioactivity

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What are the three types of radiation?
Alpha, Beta and Gamma
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Why are some substances radioactive?
The atoms of a radioactive substance each have a nucleus that is unstable.
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How does an unstable nucleus become stable?
They emit alpha, beta and gamma radiation to become stable.
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What are examples of background radiation?
This is radiation from radioactive substances, such as: in the environment, from space (cosmic rays), from devices such as Xray tubes.
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What is an ion?
An ion is a charged particle that is formed when an atom gains or loses one or more electrons. Then there are unequal numbers of protons and electrons.
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What are isotopes?
Isotopes are atoms of the same element with different numbers of neutrons.
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What happens when an unstable nucleus emits an alpha particle?
Its atomic number goes down by 2 and its mass number goes down by 4. For example, the thorium isotope 228, 90 Th decays by emitting an alpha particle, forming the radium isotope 224, 88 Ra.
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What happens when an unstable nucleus emits a beta particle?
Its atomic number goes up by 1 and its mass number stays the same. For example, the potassium isotope 40, 19 K decays by emitting a beta particle, forming a nucleus of the calcium isotope 40, 20 Ca.
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Whats the penetrating power of alpha, beta and gamma radiation?
Alpha radiation can penetrate through a thin sheet of paper. Beta radiation can penetrate through an aluminium and lead sheet. Gamma radiation can penetrate through a thick lead sheet and concrete.
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How is beta radiation deflected by a magnetic field?
Beta radiation is easily deflected in the same way as electrons. Beta radiation consists of negatively charged particles and is emitted by an unstable nucleus that contains too many neutrons.
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How is alpha radiation deflected by a magnetic field?
Alpha radiation is deflected in the opposite direction to beta radiation and is much harder to deflect. Alpha radiation consists of positively charged particles and an alpha particle is two protons and two neutrons stuck together.
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How is gamma radiation deflected by a magnetic field?
Gamma radiation is not deflected by a magnetic field. This is because gamma radiation is an electromagnetic radiation so is uncharged.
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What are the dangers of radioactivity?
The radiation from radioactive substances can knock electrons out of atoms, causing the atoms to become charged because they lose electrons. This is called ionisation. Ionisation in a living cell can damage or kill the cell.
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What is a geiger counter used for?
A geiger counter collects the charged ions and can measure the amount of ionisation that is taking place in a certain time by radioactive substances.
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What is the half-life of an isotope?
The half-life is the time for decay rate-number of nuclei to halve.
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Purposes of using radioactivity?
Radioactivity is used in: medicine to kill cancer, industry to detect thickness of material, dating materials to find out how old things are.
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Other cards in this set

Card 2

Front

Why are some substances radioactive?

Back

The atoms of a radioactive substance each have a nucleus that is unstable.

Card 3

Front

How does an unstable nucleus become stable?

Back

Preview of the front of card 3

Card 4

Front

What are examples of background radiation?

Back

Preview of the front of card 4

Card 5

Front

What is an ion?

Back

Preview of the front of card 5
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