FOCUS ON: Half-lives

Part 1 - Keywords:

1. Radioactive decay

2. Half-life

3. Isotope

4. Nuclei

5. Count rate

6. Activity

Part 2 - Key Facts:

1. Radioactive decay is a random process in which unstable nuclei of radioactive isotopes undergo spontaneous transformation.

2. The half-life of a radioactive isotope is the time it takes for the number of nuclei of the isotope in a sample to halve.

3. Alternatively, the half-life is the time it takes for the count rate (or activity) from a sample containing the isotope to fall to half its initial level.

Part 3 - Quick Quiz:

1. What does the term "half-life" refer to in radioactive decay?

   a) The time it takes for all nuclei in a sample to decay

   b) The time it takes for the count rate to double

   c) The time it takes for the number of nuclei in a sample to halve

   Answer: c) The time it takes for the number of nuclei in a sample to halve

2. If a sample of a radioactive isotope has a half-life of 10 years, how much of the original sample will remain after 20 years?

   a) One-quarter

   b) One-third

   c) One-half

   Answer: a) One-quarter

3. How is the activity of a radioactive sample related to its half-life?

   a) The activity increases as the half-life decreases

   b) The activity decreases as the half-life decreases

   c) There is no relationship between activity and half-life

   Answer: b) The activity decreases as the half-life decreases

Part 4 - Going Further:

Question: Explain why the concept of half-life is important in various fields, such as medicine and archaeology.

Answer: The concept of half-life is essential in medicine for determining the rate of decay of radioactive isotopes used in diagnostic imaging and cancer treatment. In archaeology, it helps estimate the age of artefacts by analysing the decay of radioactive isotopes present in them. Understanding half-life allows scientists to predict the decay rate of isotopes and make informed decisions about their applications.

Part 5 - Revision Tips:

To grasp the concept of half-life, practice solving problems involving radioactive decay and half-life calculations. Understand how to interpret half-life data and its significance in various contexts.

Part 6 - More Help:

Stay tuned for the next issue, where we'll explore another intriguing topic in GCSE Science.

We will be taking a break over the half term next week. We will be back on the 26th February