Mass number, atomic number and isotopes

There are different isotopes of the element carbon.

When carbon-14 decays into nitrogen-14, it emits beta radiation.

Complete the equation for the decay of carbon-14.

Carbon-14 has a half-life of 5700 years.

Explain what half-life means.

Alpha particles, beta particles, and gamma rays can penetrate different types and thicknesses of material.

Draw one line from each type of radiation to the type and maximum thickness of material radiation is able to penetrate.

Type of radiation
Type and maximum thickness of material

Describe one similarity and one difference between a nucleus of iodine-127 and a nucleus of iodine-131.

Iodine-131 is radioactive.

The graph shows how the activity of a sample of iodine-131 changes over time.

Use the graph to show that the half-life of iodine-131 is approximately 8 days.

Show your working on the graph.

Iodine-131 is used as a medical tracer and for radiotherapy when treating cancer patients.

A radiologist injects a patient with a dose of iodine-131. The dose has an initial activity of 4.00 MBq.

Calculate the number of days it takes the activity to reduce to 0.25 MBq.

The radiologist wears gloves and a film badge while handling iodine-131.

The film badge contains photographic film which turns dark when exposed to ionising radiation.

Explain how using the gloves and the film badge reduces risks to the radiologist’s health.

This question is about radioactivity.

Some atoms and isotopes of elements are shown.

Which statements are correct for these atoms and isotopes? Tick (✓) three boxes.

Thorium‑234 decays by emitting beta radiation.

What happens to the mass number and charge of a nucleus of thorium‑234 when it decays?

Draw one line from each quantity to what happens.

Why do some atoms emit nuclear radiation?

The diagram shows how the amount of a radioactive element changes over a total of 30 days.

Calculate the half‑life of this radioactive element.

When uranium‑238 decays, it forms isotopes of different elements.

The graph shows part of the decay chain produced when uranium‑238 decays.

Circle two points on the graph which are isotopes of the same element.

Explain how you worked out your answer.

(b) Describe what happens to the atomic number and mass of a nucleus of²³⁴Th as it decays into (i) ²³⁴Pa.

Which type of radiation is emitted when²³⁴Th decays into²³⁴Pa? (ii)

Eventually the isotope²⁰⁶Pb is formed and the decay chain stops. (d)

Explain why the decay chain stops at²⁰⁶Pb.

The table shows information about the number of protons, neutrons and electrons in different

Which two atoms are isotopes?

A 1 and 2

B 1 and 3

C 2 and 3

D 3 and 4

A scientist measures the activity of a radioactive isotope. She uses a Geiger-Muller tube connected to a counter.

Table 12.1 shows her results.

What is the mean activity of the isotope?

Is there a pattern in the results in Table 12.1 ?

Explain your answer using ideas about radioactivity.

Carbon-12 is a stable isotope. Carbon-14 is an unstable radioactive isotope.

Table 12.2 shows the contents of each nucleus.

Explain why carbon-12 and carbon-14 are isotopes.

This is the equation for the radioactive decay of carbon-14:

What happens to the nuclear mass (mass number) when carbon-14 decays?

Americium-241 is a radioactive isotope used in smoke alarms.

Table 12.3 shows how the activity of americium-241 changes.

What is meant by the half-life of an isotope?

Use the data in Table 12.3 to calculate the half-life of americium-241.

This is a diagram of a smoke alarm.

Smoke enters the smoke alarm, which blocks the radiation emitted by the americium-241.

A smoke alarm company decides to use a different isotope.

Table 12.4 shows the three choices of isotope.

Which isotope, A, B or C, is the best to use in a smoke alarm?

Tick (✓) one box.

Explain your answer using the information in Table 12.4.

Carbon-12 is a stable isotope. Carbon-14 is an unstable radioactive isotope.

Describe what is meant by the term isotope.

This is the equation for the radioactive decay of carbon-14:

Which type of radiation is emitted by carbon-14?

Describe how the mass and charge of the nucleus changes when the carbon-14 decays.

Mass........

Charge........

Carbon-14 can be used to date ancient objects.

An ancient object is 17 100 years old. The half-life of carbon-14 is 5700 years.

For the ancient object, what is the ratio of the original amount of carbon-14 to the amount of carbon-14 left?

Which statement is true for isotopes of the same element?

N_p = number of protons and N_n = number of neutrons.

A N_p = N_n

B N_p is the same but N_n is different

C N_p is always greater than N_n

D The total (N_p + N_n) is always the same

This question is about radioactivity.

A teacher shows his class an experiment. The teacher wants to identify the type of radiation given out by a radioactive isotope.

He uses a Geiger-Muller tube connected to a counter to measure the count rate.

He places different materials between the radioactive isotope and the Geiger-Muller tube.

The table shows the count rate for different materials.

Suggest why the teacher places lead around most of the radioactive isotope.

There are three types of radiation, alpha, beta and gamma.

Which type of radiation is given out by the radioactive isotope?

Explain your answer.

Use the data in the table to help.