Contextualization

Radioactivity is a natural or artificial phenomenon by which some substances or chemical elements, called radioactive, are capable of emitting radiation, which have the property of impressing photographic plates, ionizing gases, producing fluorescence, and passing through opaque bodies to light. Today, radioactivity is used in various ways that benefit humans, such as in nuclear medicine, in nuclear power plants, in the sterilization of materials and food, among others.

Within the theme of radioactivity, one of the fundamental concepts is that of half-life, also known as the half-life period. The half-life of a radioactive substance is the time required for half of the nuclei in a sample to disintegrate. This is a constant value for each radioactive ion and is independent of the amount of the sample, that is, even if the sample is large or small, the half-life does not change.

Importance of Half-Life

Understanding and being able to calculate the half-life not only helps us understand how radioactive isotopes decay, but it also has many practical uses in medicine, archaeology, and geology. In medicine, radioisotopes are used to diagnose and treat diseases. For this purpose, it is necessary to know the half-life of the isotope in order to calculate the time required for the radiation to decrease to safe levels.

In archaeology, the half-life of carbon-14 is of great value for dating ancient artifacts. In geology, it is used for dating rocks and minerals. This is because the Earth is a closed system and some elements convert into others over time. Knowing the half-life of these processes, we can estimate the age of the rocks.

Hands-on Activity

Activity Title: Half-Life Matters!

Project Goal

This project aims to allow students to explore the concept of half-life through a fun and collaborative activity that involves simulating radioactive decay using common and safe materials. The data collected will then be used to calculate the half-life and compare it with a known theoretical value.

Detailed Project Description

The groups, composed of 3 to 5 students, will simulate the radioactive decay process using Lego pieces (or any other small and countable object) and a box. They will perform several "generations" of this simulation and record the number of "atoms" remaining after each "generation". Based on this data, they will be able to calculate the half-life.

Required Materials

• Lego pieces or any other small and countable object (about 100 pieces for each group);
• Shoe box or similar;
• Spreadsheet to record data;
• Calculator.

Detailed Step-by-Step Instructions for the Activity

1. Fill the box with Lego pieces. Each piece represents a radioactive atom.

2. Shake the box to simulate radioactive decay. After shaking, remove the pieces that fall out of the box, representing the atoms that have decayed.

3. Count the remaining pieces in the box (atoms that have not decayed) and write this number in the spreadsheet.

4. Repeat steps 2 and 3 as many times as necessary (suggestion: 10 times).

5. Based on the data collected, calculate the half-life in "generations". One tip is to look for the generation where the number of pieces has dropped by half.

6. Compare the half-life with a known theoretical value. Discuss the possible reasons for the differences.

As the hands-on activity is carried out, students should keep a detailed record of their findings, which will be compiled into a final report.

Project Deliverables

At the end of the week, students should submit a written report containing:

1. Introduction: Contextualization of the theme, its relevance and application in the real world, objective of this project.

2. Development: Details of the theory of the central theme of the project (half-life), detailed explanation of the activity, description of the methodology used, presentation, and discussion of the results obtained.

3. Conclusion: Review of the main points, explanation of the lessons learned, and conclusions drawn about the project.

4. Bibliography: Indication of the sources used to work on the project such as books, web pages, videos, etc.

The report will be evaluated based on the clarity of the concepts presented, the accuracy of the calculations performed, the critical reflection on the results obtained, and the overall quality of the presentation. Special attention will be given to collaboration and teamwork, as well as time management skills.