What does it mean that radioactive decay is random?

You cannot predict when a particular nucleus will decay.

What is an alpha particle?

A helium nucleus: 2 protons and 2 neutrons, charge +2.

What is a beta particle?

A fast-moving electron emitted from the nucleus, charge -1.

What is gamma radiation?

A high-energy electromagnetic wave with no charge.

What stops alpha radiation?

A sheet of paper or a few centimetres of air.

What stops beta radiation?

A few millimetres of aluminium.

How are alpha, beta and gamma affected by electric and magnetic fields?

Alpha and beta are deflected in opposite directions (beta more); gamma is not deflected.

Name three sources of background radiation.

Radon gas from rocks, cosmic rays and food (also medical X-rays and nuclear fallout).

What does a Geiger-Muller tube measure?

The count rate of ionising radiation.

How does alpha decay change the mass number and atomic number?

Mass number decreases by 4 and atomic number decreases by 2.

How does beta decay change the mass number and atomic number?

Mass number stays the same and atomic number increases by 1.

Radioactive decay and types of radiationIB MYP Physics: Flashcards

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What does it mean that radioactive decay is spontaneous?

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What does it mean that radioactive decay is spontaneous?: It happens without any outside trigger and is not affected by temperature or chemical reactions.
What does it mean that radioactive decay is random?: You cannot predict when a particular nucleus will decay.
What is an alpha particle?: A helium nucleus: 2 protons and 2 neutrons, charge +2.
What is a beta particle?: A fast-moving electron emitted from the nucleus, charge -1.
What is gamma radiation?: A high-energy electromagnetic wave with no charge.
What stops alpha radiation?: A sheet of paper or a few centimetres of air.
What stops beta radiation?: A few millimetres of aluminium.
What reduces gamma radiation?: Thick lead or concrete.
Which radiation is most strongly ionising?: Alpha.
How are alpha, beta and gamma affected by electric and magnetic fields?: Alpha and beta are deflected in opposite directions (beta more); gamma is not deflected.
Name three sources of background radiation.: Radon gas from rocks, cosmic rays and food (also medical X-rays and nuclear fallout).
What does a Geiger-Muller tube measure?: The count rate of ionising radiation.
How does alpha decay change the mass number and atomic number?: Mass number decreases by 4 and atomic number decreases by 2.
How does beta decay change the mass number and atomic number?: Mass number stays the same and atomic number increases by 1.

Exam questions on Radioactive decay and types of radiation

A hospital physicist in Manchester stores three radioactive sources, one that emits alpha particles, one that emits beta particles and one that emits gamma rays. She must choose suitable shielding for each source and check which types of radiation are most harmful to living cells.
Compare the ionising power and the penetrating power of alpha particles and gamma rays.2 marks
Uranium-238 has atomic number 92. Its nuclei are unstable. A uranium-238 nucleus decays by emitting an alpha particle and forms a nucleus of thorium (symbol Th). The thorium-234 nucleus then decays by beta emission to form protactinium (symbol Pa).
State the mass number and the atomic number of the thorium nucleus formed when uranium-238 decays by alpha emission.2 marks
A student investigates how well two materials absorb gamma radiation. She holds a Geiger-Muller tube 10 cm from a gamma source and records the number of counts in 60 seconds. With the source removed she records a background count of 12 in 60 seconds. With nothing between the source and the tube she records 612 counts. With a 5 mm sheet of aluminium in the way she records 598 counts, and with a 5 mm sheet of lead in the way she records 214 counts.
Identify the independent variable, the dependent variable and one control variable in this investigation.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).