Understanding the Particulate Nature of Matter and Atomic Structure Chemistry SS 1 First Term Lesson Notes Week 4

Chemistry SS 1 First Term Lesson Notes – Week 4

Subject: Chemistry
Class: SS 1
Term: First Term
Week: 4
Age: 14-16 years
Topic: Particulate Nature of Matter II
Sub-Topic: (1) Dalton’s Atomic Theory, (2) Atomic Structure, (3) Constituents of Atoms, (4) Arrangement of Electrons, (5) Atomic Number and Mass Number, (6) Relative Atomic Mass

Duration: 40 minutes

Behavioral Objectives:

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

1. Explain Dalton’s atomic theory.
2. Describe the atomic structure.
3. Identify the constituents of atoms: protons, neutrons, and electrons.
4. Explain the arrangement of electrons around the nucleus.
5. Differentiate between atomic number, mass number, and isotropy.
6. Understand relative atomic mass with reference to C-14 isotope.

Keywords: Atomic theory, atomic structure, protons, neutrons, electrons, atomic number, mass number, isotropy, C-14 isotope.

Set Induction:

Ask students to consider the makeup of any substance around them and introduce the idea that matter consists of tiny particles called atoms.

Entry Behavior:

Basic understanding of particles and matter from previous lessons.

Learning Resources and Materials:

• Periodic table
• Atomic models or visual aids of atomic structure
• Diagrams of electron arrangements

Building Background/Connection to Prior Knowledge:

Revisit prior discussion on elements and compounds, introducing the atom as the building block of matter.

Embedded Core Skills:

• Critical thinking
• Observation
• Analysis

Learning Materials:

• Lagos State Scheme of Work
• Chemistry textbooks

Instructional Materials:

• Whiteboard/Markers
• Atomic models and visual representations of atoms

Content

Dalton’s Atomic Theory

1. Key Points:
   • Matter is made up of tiny particles called atoms.
   • Atoms of the same element are identical in mass and properties.
   • Compounds are formed by the combination of different atoms.
   • Atoms are indivisible and cannot be created or destroyed in chemical reactions.

Atomic Structure

1. Atoms consist of a nucleus containing protons and neutrons.
2. Electrons orbit the nucleus in regions known as energy levels or shells.

Constituents of Atoms

• Protons: Positively charged particles found in the nucleus.
• Neutrons: Neutral particles in the nucleus.
• Electrons: Negatively charged particles orbiting the nucleus.

Arrangement of Electrons

• Electrons are arranged in shells or energy levels around the nucleus.
• Each shell can hold a specific number of electrons.

Atomic Number, Mass Number, and Isotropy

1. Atomic Number (Z): The number of protons in an atom’s nucleus.
2. Mass Number (A): The total number of protons and neutrons in the nucleus.
3. Isotropy (Isotopes): Atoms of the same element with different mass numbers due to varying numbers of neutrons.

Relative Atomic Mass (Based on C-14 Isotope)

• The relative atomic mass is calculated by comparing the mass of an atom to 1/12th the mass of a C-14 (carbon-14) isotope.

Presentation

Step 1: Explain Dalton’s Atomic Theory

• Teacher’s Activity: Discuss Dalton’s theory with key points.
• Learners’ Activity: Share their understanding of atoms based on Dalton’s model.

Step 2: Describe Atomic Structure

• Teacher’s Activity: Use diagrams to illustrate the nucleus and electron shells.
• Learners’ Activity: Identify parts of an atom in the diagram.

Step 3: Constituents of Atoms

• Teacher’s Activity: Explain protons, neutrons, and electrons.
• Learners’ Activity: Relate charges to each constituent and discuss their functions.

Step 4: Arrangement of Electrons

• Teacher’s Activity: Show how electrons are arranged in energy levels.
• Learners’ Activity: Identify how many electrons can fit in each shell.

Step 5: Atomic Number, Mass Number, and Isotropy

• Teacher’s Activity: Define atomic number, mass number, and isotropy with examples.
• Learners’ Activity: Differentiate between isotopes based on neutron count.

Step 6: Relative Atomic Mass Based on C-14

• Teacher’s Activity: Explain how relative atomic mass is determined with reference to the C-14 isotope.
• Learners’ Activity: Discuss why C-14 is used as a standard for comparison.

Fill-in-the-Blank Questions

1. Dalton proposed that matter is composed of tiny __________ called atoms.
   • a) particles
   • b) waves
   • Answer: a) particles
2. __________ are positively charged particles in the nucleus.
   • a) Neutrons
   • b) Protons
   • Answer: b) Protons
3. __________ are neutral particles in an atom’s nucleus.
   • a) Protons
   • b) Neutrons
   • Answer: b) Neutrons
4. __________ orbit the nucleus and have a negative charge.
   • a) Protons
   • b) Electrons
   • Answer: b) Electrons
5. The atomic number represents the number of __________ in the nucleus.
   • a) protons
   • b) electrons
   • Answer: a) protons
6. The mass number is the total number of protons and __________.
   • a) electrons
   • b) neutrons
   • Answer: b) neutrons
7. __________ are atoms with the same number of protons but different numbers of neutrons.
   • a) Isotopes
   • b) Molecules
   • Answer: a) Isotopes
8. The relative atomic mass of an element is based on the isotope __________.
   • a) C-14
   • b) O-16
   • Answer: a) C-14
9. Electrons occupy regions called __________ around the nucleus.
   • a) orbits
   • b) shells
   • Answer: b) shells
10. A proton has a __________ charge.
    • a) positive
    • b) negative
    • Answer: a) positive
11. Atoms of the same element with different __________ are isotopes.
    • a) masses
    • b) charges
    • Answer: a) masses
12. The __________ holds protons and neutrons in an atom.
    • a) nucleus
    • b) electron shell
    • Answer: a) nucleus
13. Dalton’s atomic theory states that atoms are __________.
    • a) divisible
    • b) indivisible
    • Answer: b) indivisible
14. __________ are responsible for the chemical properties of atoms.
    • a) Protons
    • b) Electrons
    • Answer: b) Electrons
15. A __________ is the smallest unit of an element that retains its properties.
    • a) molecule
    • b) atom
    • Answer: b) atom

Frequently Asked Questions

1. What is Dalton’s atomic theory?
   A theory that describes matter as composed of tiny, indivisible particles called atoms.
2. What are protons?
   Positively charged particles found in the nucleus.
3. What are neutrons?
   Neutral particles in the nucleus.
4. What are electrons?
   Negatively charged particles orbiting the nucleus.
5. What is the atomic number?
   The number of protons in an atom’s nucleus.
6. What is the mass number?
   The total number of protons and neutrons in the nucleus.
7. What is an isotope?
   Atoms of the same element with different numbers of neutrons.
8. What is the C-14 isotope?
   A carbon isotope used as a standard for relative atomic mass.
9. What is atomic structure?
   The arrangement of particles (protons, neutrons, and electrons) in an atom.
10. What is a nucleus?
    The central part of an atom containing protons and neutrons.
11. What is the charge of an electron?
    Negative.
12. What is the role of neutrons?
    Neutrons stabilize the nucleus.
13. How are electrons arranged in atoms?
    In energy levels or shells.
14. Why are isotopes important?
    They help understand atomic mass variations in elements.
15. What is relative atomic mass?
    A comparison of an atom’s mass to 1/12th of a C-14 isotope.

Evaluation Questions

1. Describe Dalton’s atomic theory.
2. What particles make up the nucleus?
3. Explain the term “atomic number.”
4. Differentiate between mass number and atomic number.
5. Define isotropy with an example.
6. State the charge of a neutron.
7. What is relative atomic mass?
8. Describe the arrangement of electrons.
9. Why is C-14 used in atomic mass calculations?
10. How do protons affect an atom’s properties?

Conclusion

Summarize the atomic theory, atomic structure, and the importance of protons, neutrons, and electrons in understanding atomic behavior.