Basic Science and Technology - Junior Secondary 3 - Radioactivity

Radioactivity

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TERM: 3RD TERM

WEEK: 3

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. ) Define radioactivity and discuss who and how it was discovered
  2. ) Define radioactive elements and give examples
  3. ) State and explain the types of radioactive elements

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 defines radioactivity.

Learners pay attention and participate

STEP 3

Explanation

He defines radioactive elements and gives examples. He then states and explain the types of radioactive elements

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

Radioactivity is the process by which unstable atomic nuclei lose energy by emitting radiation in the form of particles or electromagnetic waves. This phenomenon occurs naturally in certain elements and can also be induced artificially.

 

Radioactivity was discovered by Henri Becquerel in 1896 while experimenting with uranium salts. Becquerel noticed that uranium emitted rays that could expose photographic plates, even without the presence of sunlight. Later, Marie Curie and Pierre Curie conducted further research, isolating and studying new radioactive elements like polonium and radium.

 

Radioactive Elements

Radioactive elements are elements that have unstable atomic nuclei. These elements release radiation as they decay into more stable forms. Their nuclei break down spontaneously, emitting radiation in the process.

Examples of Radioactive Elements:

    • Uranium (U): Used in nuclear reactors and weapons.
    • Radon (Rn): A naturally occurring gas from the decay of radium.
    • Thorium (Th): Found in trace amounts in the Earth's crust.
    • Plutonium (Pu): Used in nuclear weapons and reactors.

Types of Radioactive Elements

  • Alpha (α) Emitters: Elements that emit alpha particles during decay. Alpha particles are composed of two protons and two neutrons. These elements typically have large atomic numbers. Examples: Uranium-238, Radium-226.
  • Beta (β) Emitters: These elements emit beta particles (electrons or positrons). Beta radiation occurs when a neutron in the nucleus transforms into a proton, emitting an electron or positron. Examples: Carbon-14, Strontium-90.
  • Gamma (γ) Emitters: These elements emit gamma rays, a form of high-energy electromagnetic radiation, usually after alpha or beta decay. Gamma radiation does not change the atomic number of the element. Examples: Cobalt-60, Iodine-131.

 

EVALUATION:

  1. Explain the process of radioactivity and how it contributes to the decay of unstable atomic nuclei.
  2. Who discovered radioactivity, and what was the significance of Henri Becquerel's experiment with uranium salts?
  3. List and describe the types of radioactive elements, providing examples and explaining the particles they emit.
  4. What are the uses of uranium, radon, thorium, and plutonium, and why are these elements considered radioactive?
  5. Compare and contrast alpha, beta, and gamma radiation in terms of their properties, examples, and penetration abilities.

CLASSWORK: As in evaluation

CONCLUSION: The teacher marks their books and commends them positively