**Lesson Plan for Senior Secondary 1 Chemistry: Atomic Number, Relative Atomic Masses, Isotopes, and Calculations**
**Lesson Duration:** 90 minutes
**Objective:**
By the end of this lesson, students will be able to:
1. Define and differentiate between atomic number, mass number, and relative atomic masses.
2. Explain isotopes and give examples.
3. Perform basic calculations involving atomic masses and isotopes.
**Materials Needed:**
- Periodic Table of Elements (Individual copies for students)
- Whiteboard and markers
- Projector and laptop for presentation slides
- Worksheets for practice problems
- Scientific calculators
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### Lesson Structure:
**I. Introduction (10 minutes)**
1. **Greeting and Roll Call**
- Briefly greet the students and take attendance.
2. **Hook/Starter Activity**
- Show a short video or fun fact about the discovery of atomic number and isotopes.
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**II. Direct Instruction (30 minutes)**
1. **Presentation Slide: Atomic Number and Mass Number**
- Definition of atomic number (number of protons in the atom).
- Definition of mass number (sum of protons and neutrons).
- How to read these values from the periodic table.
2. **Presentation Slide: Relative Atomic Masses**
- Explain what relative atomic mass is.
- Discuss how it is different from the mass number.
3. **Presentation Slide: Isotopes**
- Define isotopes and provide examples (e.g., Carbon-12, Carbon-14).
- Explain how isotopes maintain the same chemical properties but differ in mass number.
4. **Presentation Slide: Calculations Involving Isotopes**
- Show how to calculate the relative atomic mass when given the abundance of isotopes.
- Example calculation: Chlorine's relative atomic mass.
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**III. Guided Practice (20 minutes)**
1. **Example Problems in Groups**
- Divide students into small groups.
- Hand out worksheets with example problems.
- Walk around to assist and answer questions.
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**IV. Independent Practice (20 minutes)**
1. **Individual Worksheet**
- Provide a set of practice problems for individual work.
- Include problems where students must identify atomic number and mass number, perform calculations with isotopic abundance, and compare isotopes.
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**V. Review and Recap (10 minutes)**
1. **Q&A Session**
- Open the floor for students to ask any questions about the material covered.
2. **Quick Recap**
- Summarize the key points of the lesson: Atomic number, relative atomic mass, isotopes, and how to perform basic calculations involving isotopes.
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**VI. Assessment (throughout lesson)**
- Monitor students' understanding through group and independent practice.
- Assess participation and comprehension through Q&A.
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**VII. Homework Assignment**
1. **Worksheet**
- Assign additional problems for homework to reinforce the day’s lesson, touching on all areas covered.
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**VIII. Closing Remarks (5 minutes)**
1. **Preview of Next Lesson**
- Give students a brief overview of what will be covered in the next class.
2. **Class Dismissal**
- Thank students for their participation and dismiss the class.
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**Additional Notes:**
- Make sure to provide additional resources such as video links, textbook chapters, or websites for students who need extra help.
- Encourage students to form study groups to help each other understand difficult concepts.
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**End of Lesson Plan**