Topic: Simple Molecules and Covalent Bonds
Lesson 1: Covalent Bonds
| Section | Details |
|---|---|
| Objective | State that a covalent bond is formed when a pair of electrons is shared between two atoms, leading to noble gas electronic configurations. |
| Activities | – Starter (5 mins): Discuss the octet rule and why atoms form bonds (stability of noble gases). – Main (25 mins): 1. Define covalent bonding as sharing electrons. 2. Use examples (e.g., H₂, Cl₂) to show how sharing electrons leads to stable configurations. 3. Introduce the concept of single, double, and triple bonds. – Plenary (10 mins): Students explain why covalent bonding occurs using examples of hydrogen and chlorine. |
| Resources | Diagrams of covalent bonds, animations/videos, dot-and-cross templates. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write definitions of covalent bonding and provide examples of molecules with single, double, and triple bonds. |
| Assessment | Worksheet: Identify whether given bonds are ionic or covalent. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/21 Q2(b) – Identifying covalent bonds and explaining their formation. |
Lesson 2: Formation of Covalent Bonds in Simple Molecules
| Section | Details |
|---|---|
| Objective | Describe the formation of covalent bonds in simple molecules (e.g., H₂, Cl₂, H₂O, CH₄, NH₃, HCl, CH₃OH, C₂H₄, O₂, CO₂, N₂) using dot-and-cross diagrams. |
| Activities | – Starter (5 mins): Show a periodic table and discuss how non-metals bond covalently. – Main (25 mins): 1. Draw dot-and-cross diagrams for simple molecules (e.g., H₂, CH₄). 2. Highlight double bonds (O₂, CO₂) and triple bonds (N₂). 3. Explain the sharing of electrons in terms of achieving stable configurations. – Plenary (10 mins): Students practice drawing diagrams for NH₃, HCl, and CH₃OH. |
| Resources | Dot-and-cross templates, periodic table, molecule diagrams. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Draw dot-and-cross diagrams for O₂, N₂, and C₂H₄. |
| Assessment | Worksheet: Draw dot-and-cross diagrams for provided molecules. |
| Past Paper Practice | IGCSE Chemistry 0620/41/M/J/20 Q3(c) – Drawing dot-and-cross diagrams for covalent molecules. |
Lesson 3: Properties of Simple Molecular Compounds
| Section | Details |
|---|---|
| Objective | Describe and explain the properties of simple molecular compounds in terms of structure and bonding: (a) low melting and boiling points, (b) poor electrical conductivity. |
| Activities | – Starter (5 mins): Ask: Why do ice cubes melt easily compared to salt? (Introduce intermolecular forces). – Main (25 mins): 1. Explain low melting/boiling points due to weak intermolecular forces. 2. Discuss poor electrical conductivity due to absence of free electrons or ions. 3. Compare the properties of molecular compounds (e.g., water, CO₂) with ionic compounds (e.g., NaCl). – Plenary (10 mins): Group activity: Classify a list of compounds as having high or low melting points and explain why. |
| Resources | Molecular models, diagrams of bonding, worksheets for classification. |
| Time | 40 minutes total: 5 mins (Starter) + 25 mins (Main) + 10 mins (Plenary). |
| Homework | Write explanations for the low melting point and poor conductivity of simple molecular compounds. |
| Assessment | Worksheet: Compare the properties of ionic and covalent compounds based on their structure and bonding. |
| Past Paper Practice | IGCSE Chemistry 0620/41/O/N/20 Q3(d) – Properties of molecular compounds based on structure and bonding. |
Notes for Teachers:
- Use visual aids (animations, molecular models) to make abstract concepts tangible.
- Encourage students to practice drawing dot-and-cross diagrams for a variety of molecules.
- Relate the properties of molecular compounds to real-world examples (e.g., why water boils at 100°C but salt melts at much higher temperatures).
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