Lesson 2: 3.2 Properties of Solids
Duration of Days: 1
Lesson Objective
Explain the relationship between the structures of different types of solids and their macroscopic properties.
How does the atomic or molecular layout of a solid dictate its mechanical, thermal, and electrical properties?
Why does a diamond (covalent network) have a drastically higher melting point than a block of ice (molecular solid)?
Covalent Network
Molecular Solid
Ionic Solid
Amorphous
Crystalline Allotropes
Brittle
Learning Objective 3.2.A; Suggested Skill 4.C (Model Analysis - Connecting scales)
Students categorize solids into four groups: ionic, covalent network, molecular, and metallic. They must connect the particulate forces keeping the solid intact to physical properties such as melting point, hardness, malleability, and electrical conductivity.
Support: Use a 2x2 graphic organizer matrix that sorts solids by "Particles at Lattice Points" and "Attractive Force Holding Lattice Together."
Extension: Provide a list of carbon allotropes (graphite vs. diamond) and have students explain why graphite conducts electricity and acts as a lubricant, while diamond is an insulator and incredibly hard.
Classify each of the following solids as ionic, covalent network, molecular, or metallic, and rank them in order of increasing melting point: SiO2(s), I2(s), KTaO3(s). Justify your ranking using particulate structures.