Properties of Radiation (Edexcel IGCSE Physics (Modular): Unit 2)

Radon is a gas produced by some types of rocks.

Radon is a natural source of radioactivity.

What is the name for this radioactivity?

Radon-222 and radon-220 are both isotopes of radon. A nucleus of radon-222 has 86 protons.

How many protons are there in a nucleus of radon-220?

Radon-222 and radon-220 are both isotopes of radon. A nucleus of radon-222 has 136 neutrons.

How many neutrons are there in a nucleus of radon-220? 

Which of these particles has the largest charge? 

Which of these particles has the largest mass? 

The maximum range of a beta particle in air is about

When a nucleus emits a beta particle 

When an unstable nucleus emits an alpha particle, its atomic (proton) number 

Which of these has a mass (nucleon) number of 4? 

Which of these is the most ionising? 

When an unstable nucleus emits an alpha particle, its mass (nucleon) number 

lodine-131 is a radioactive isotope that emits beta particles. 

The equation for this decay is  

The mass (nucleon) number for Xe is 

The atomic (proton) number for iodine-131 is 

Which of these describes what happens to the strontium-90 nucleus when it emits a beta particle?  

Tritium is an isotope of hydrogen that decays by emitting beta particles. It is used in some luminous signs. 

The symbol for tritium is .

(i) Determine the number of protons and the number of neutrons in a single atom of tritium.

(2)

(ii) Describe three differences between an alpha particle and a beta particle.

(3)

(iii) Suggest why tritium cannot emit alpha particles.

(1)

Tritium is used in this luminous sign.

In this sign

• The letters are made up of glass tubes containing tritium gas

• The inside of each tube is coated with a phosphor

• The phosphor emits light when beta particles hit it

Suggest why this sign is safe to use even though beta particles are ionising and can be dangerous.

A teacher uses this apparatus to demonstrate radioactivity to his students.

The teacher needs to take some safety precautions.

Put one tick (✓) on each row to show whether the safety precaution is needed or not. Two have been done for you.

The teacher uses this method to investigate radioactivity.

• Place the detector 10 cm from the radioactive source

• Record the count with different absorbent materials between the source and the detector

• Repeat the investigation using a different radioactive source

• Also repeat the investigation without a source

The table shows his results.

(i) State why the teacher keeps the distance constant between the source and the detector. 

(1)

(ii) Explain why there is a reading when no source is used.

(2)

(i) Explain which of the materials the teacher used is the best absorber of radiation.

(3)

(ii) A student makes this conclusion.

'Stone is the worst absorber of radiation.'

Evaluate this conclusion

(3)

The table describes the nuclei of four atoms.

(i) Which two nuclei have the same number of protons? 

(1)

(ii) Which two nuclei have the same number of nucleons? 

(1)

(iii) Which two nuclei have the same number of neutrons? 

(1)

All of the nuclei are unstable and have a different half-life. 

(i) Explain what is meant by the term unstable.

(1)

(ii) Explain what is meant by the term half-life

(2)

When plutonium decays, it emits an alpha particle and a gamma ray.

(i) Complete the decay equation for plutonium-238.

(4)

(ii) Use information from the table in part (a) to identify element X.

(1)

The nucleus of americium-238 can absorb an electron. When this happens, one of the protons in the nucleus becomes a neutron.

This equation describes the process.

(i) Describe how this process affects the proton number and the nucleon number of the nucleus that absorbs the electron.

(2)

(ii) Identify the new nucleus formed by this process.

(1)

The table shows the nature of alpha and beta particles. 

Explain why alpha particles and beta particles have different penetrating powers. 

A doctor uses gamma radiation to produce an image of a person's brain.

A radioactive isotope called technetium-99m is used in this process.

Technetium-99m emits gamma rays and has a short half-life.

Gamma radiation consists of 

The table describes the nuclei of four atoms.

Atoms contain electrons.

Which nucleus needs the largest number of electrons to form a neutral atom?

Tellurium-120 is an isotope of tellurium.

It has the symbol 

The number of protons, neutrons and electrons in a neutral tellurium-120 atom is

Compared to a beta particle, an alpha particle 

The grid shows the number of neutrons and the number of protons in some isotopes formed during successive radioactive decays.

(i) What are isotopes?

(2)

ii) Why are some isotopes described as stable?

(1)

(i) Use the grid in part (a) to calculate the number of neutrons in a nucleus.

(1)

(ii) Describe what happens to the number of protons and the number of neutrons when a nucleus of decays to form .

(2)

(iii) State the type of decay that occurs when decays to form .

(1)

Explain why the mass (nucleon) number and the atomic (proton) number do not change when a gamma ray is emitted from a nucleus.

Alpha particles, beta particles and gamma rays have different properties.

Complete the table by ticking the correct type of radiation for each property. The first one has been done for you.

The symbol for the structure of an alpha particle is

(i) State the number of neutrons and the number of protons in an alpha particle.

(2)

(ii) Suggest why alpha radiation is more ionising than beta or gamma radiation. 

(1)

Scientists use deflection in an electric field to help distinguish between different types of radiation.

The diagram shows a beam containing several types of radiation. This beam travels in a vacuum between two charged plates.

Some of the radiation is deflected upwards, some is deflected downwards, and some are not deflected at all. 

Put one tick in each row to show the correct deflection for each type of radiation.

One has been done for you.