Radioactivity

Subject: Basic Science
Class: JSS 3
Term: Second Term
Week: 2
Topic: Radioactivity
Sub-Topic: Meaning, History, and Examples of Radioactive Elements
Duration: 40 Minutes

Behavioral Objectives

By the end of the lesson, students should be able to:

1. Define radioactivity.
2. State the brief history of radioactivity.
3. Identify examples of radioactive elements.
4. Explain the uses of radioactive materials.

Keywords

• Radioactivity: The spontaneous emission of particles or radiation from unstable nuclei.
• Nucleus: The central part of an atom.
• Isotopes: Variants of elements with different numbers of neutrons.
• Alpha Particles: Positively charged particles emitted during radioactive decay.
• Beta Particles: Negatively charged particles emitted during radioactive decay.
• Gamma Rays: Electromagnetic waves with high energy.

Set Induction

Ask students if they have heard of X-rays or uranium. Use their responses to introduce the concept of radioactivity and its significance in everyday life.

Entry Behavior

Students are familiar with basic atomic structure (protons, neutrons, and electrons).

Learning Resources and Materials

1. Diagrams of radioactive elements.
2. Charts showing the decay of uranium.
3. Video or multimedia clips on the discovery of radioactivity.

Building Background/Connection to Prior Knowledge

Students have learned about atoms and elements in previous lessons. This lesson will build on that knowledge to explain how some elements release energy naturally.

Embedded Core Skills

• Critical thinking
• Observation
• Scientific reasoning

Reference

Lagos State Scheme of Work.

Instructional Materials

1. Glass plates (to illustrate blocking of radiation).
2. Chart showing Marie Curie and Henri Becquerel.
3. Model of uranium decay.

Lesson Content

Definition of Radioactivity

Radioactivity is the spontaneous disintegration of unstable atomic nuclei, accompanied by the emission of subatomic particles (alpha and beta particles) or electromagnetic radiation (gamma rays).

Brief History of Radioactivity

1. Henri Becquerel (1896):
   • Discovered radioactivity while studying uranium.
   • Observed that uranium could darken photographic plates even when separated by glass or black paper.
2. Marie and Pierre Curie (1898):
   • Discovered polonium and radium as radioactive elements.
   • Studied the properties of radioactive rays and their impact on matter.

Examples of Radioactive Elements

1. Uranium (U)
2. Thorium (Th)
3. Polonium (Po)
4. Radium (Ra)

Uses of Radioactivity

1. Medicine: Used in X-rays and cancer treatment.
2. Energy Production: Nuclear power plants use uranium.
3. Archaeology: Radiocarbon dating helps determine the age of ancient artifacts.
4. Agriculture: Used to preserve food by killing bacteria.

Evaluation Questions (Fill in the blanks)

Choose the correct option (a, b, c, or d).

1. Radioactivity is the ________ disintegration of unstable nuclei.
   a. Chemical
   b. Spontaneous
   c. Gradual
   d. Artificial
   Answer: b
2. Henri Becquerel discovered radioactivity in ________.
   a. 1796
   b. 1986
   c. 1896
   d. 1906
   Answer: c
3. ________ is an example of a radioactive element.
   a. Hydrogen
   b. Oxygen
   c. Uranium
   d. Sodium
   Answer: c
4. Gamma rays are a type of ________.
   a. Particle
   b. Radiation
   c. Element
   d. Metal
   Answer: b
5. Marie Curie discovered ________ and radium.
   a. Polonium
   b. Thorium
   c. Uranium
   d. Carbon
   Answer: a

Class Activity Discussion (FAQs)

1. What is radioactivity?
   Radioactivity is the natural breakdown of unstable nuclei in atoms, releasing energy in the form of particles or radiation.
2. Who discovered radioactivity?
   Henri Becquerel discovered radioactivity in 1896.
3. What are alpha particles?
   Alpha particles are positively charged particles made of two protons and two neutrons.
4. Name two uses of radioactive materials.
   Medicine (X-rays) and energy production (nuclear power).
5. Why is uranium important in nuclear power?
   Uranium is used as a fuel because it undergoes radioactive decay, releasing large amounts of energy.

Presentation Steps

1. Introduction: Revise the previous topic on atoms and elements.
2. Development:
   • Define radioactivity.
   • Discuss the historical background with visuals of Henri Becquerel and the Curies.
   • List and explain radioactive elements.
3. Student Participation:
   • Students brainstorm uses of radioactive materials.
   • Identify radioactive elements from provided materials.
4. Conclusion: Summarize key points.

Assessment Questions

1. Define radioactivity.
2. State two examples of radioactive elements.
3. Who discovered radioactivity?
4. List two uses of radioactive materials.
5. Explain the significance of gamma rays.

Answers:

1. Radioactivity is the spontaneous disintegration of unstable nuclei.
2. Uranium and polonium.
3. Henri Becquerel.
4. Medicine and energy production.
5. Gamma rays are high-energy electromagnetic radiation used in medicine and research.

Conclusion

The teacher will review the definitions, history, and uses of radioactivity. Students will provide answers to the assessment, and the teacher will provide corrections and feedback.

 

 

QUIZ START

Results

#1. Alpha particles are made of ________.

Only protons

Only electrons

Electrons and neutrons

Two protons and two neutrons

#2. ________ and radium were discovered by Marie and Pierre Curie.

Krypton

Uranium

Polonium

Thorium

#3. Radioactivity is the ________ disintegration of unstable nuclei.

Spontaneous

Chemical

Artificial

Mechanical

#4. The discovery of radioactivity was made in the year ________.

1896

1996

1796

1906

#5. The scientist who discovered radioactivity was ________.

Isaac Newton

Albert Einstein

Henri Becquerel

John Dalton

Previous

Finish