Basic Science and Technology - Junior Secondary 3 - Radioactivity

Radioactivity

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TERM: 3RD TERM

WEEK: 4

CLASS: Junior Secondary School 3

AGE: 14 years

DURATION: 40 minutes each for 2 periods

DATE:

SUBJECT: Basic Science

TOPIC: Radioactivity

SPECIFIC OBJECTIVES: At the end of the lesson, the learners should be able to

  1. ) Discuss what a Geiger-Muller tube is
  2. ) State the types of radiation and outline their properties
  3. ) Enumerate and explain some terms used in radioactivity

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, story-telling, videos from source

INSTRUCTIONAL MATERIALS: Recommended Basic Science textbooks for Junior Secondary School 3

INSTRUCTIONAL PROCEDURES: PERIOD 1-2:

PRESENTATION

TEACHER’S ACTIVITY

PUPIL’S ACTIVITY

STEP 1

Review

The teacher revises the previous lesson.

Learners pay attention

STEP 2

Introduction

He discusses what a Geiger-Muller tube is.

Learners pay attention and participate

STEP 3

Explanation

He states the types of radiation and outlines the properties of each. He enumerates and explains some terms used in radioactivity.

Learners pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a short note on the board for the learners to copy

The learners copy the note from the board

 

NOTE

RADIOACTIVITY

Geiger-Muller Tube Is

A Geiger-Muller tube (or Geiger counter) is a device used to detect and measure ionizing radiation such as alpha, beta, and gamma radiation. The tube contains gas that ionizes when radiation passes through it, creating an electrical pulse that is counted. It provides audible clicks or a digital reading that corresponds to the level of radiation present.

 

Types of Radiation and Their Properties

  • Alpha Radiation (α):
    • Composed of two protons and two neutrons.
    • Can be stopped by a sheet of paper or human skin.
    • Has low penetration ability but high ionizing power.
  • Beta Radiation (β):
    • Consists of high-speed electrons or positrons.
    • Can be stopped by materials like plastic or a few millimeters of aluminum.
    • Has moderate penetration ability and ionizing power.
  • Gamma Radiation (γ):
    • A form of electromagnetic radiation, like X-rays but with higher energy.
    • Highly penetrating, requiring thick lead or several meters of concrete to shield it.
    • Has low ionizing power but high penetration ability.

 

Some Terms Used in Radioactivity

  • Half-life: The time required for half of the atoms in a sample of a radioactive element to decay. It is a constant for each isotope.
  • Decay Chain: The sequence of decays that a radioactive element undergoes until it reaches a stable isotope.
  • Radioactive Decay: The process by which an unstable atomic nucleus loses energy by emitting radiation.
  • Radiation Shielding: Materials used to protect against radiation. Lead and concrete are commonly used to shield gamma radiation, while paper or clothing can protect against alpha radiation.
  • Isotope: Atoms of the same element with different numbers of neutrons. Some isotopes are stable, while others are radioactive.

 

EVALUATION:

  1. What is the function of a Geiger-Muller tube, and how does it detect ionizing radiation?
  2. Describe the properties of alpha, beta, and gamma radiation in terms of their composition, penetration ability, and ionizing power.
  3. What is meant by the term "half-life" in radioactivity, and why is it important for understanding radioactive decay?
  4. Explain the concept of a decay chain and give an example of how a radioactive element undergoes multiple decays before reaching a stable isotope.
  5. Discuss the significance of radiation shielding and identify materials commonly used to protect against different types of radiation.

CLASSWORK: As in evaluation

CONCLUSION: The teacher marks their books and commends them positively