Mr. Rogers' IB Design Technology Objectives
Syllabus 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter
Design Project Materials Micro Macro Struct  

IB Option B (HL Topic 8) : Microstructures and macrostructures

Unit Plan Practice Test Study Guide


Structure of Matter

  1. Define atom, molecule and ion.

  2. Outline a bond as a force of attraction between particles.

  3. Draw an equilibrium position of a particle in a bond using a general potential energy–separation curve.

  4. Define an element, compound, pure substance, mixture, alloy and composite.


  1. Draw and describe the primary bonds:

  • ionic: opposing charges of ions hold the crystal (eg NaCl) together in a lattice. Ions can often be separated easily in water but the electrons stay attached to their respective ions inside the crystal.

  • covalent: outer electrons of some atoms shared between the nuclei. Each pair of electrons shared is called a covalent bond.

  • metallic: outer electrons are freer and can flow through the crystalline structure. Bonding is caused by attraction between the positively charged metal atom nuclei and the negatively charged cloud of free electrons, and is spread throughout the lattice—“Positively charged nuclei in a sea of electrons”.

  1. State \relative strengths of primary bonds: ionic > metallic > covalent.

  2. Describe secondary bonds: weak forces of attraction between molecules

  3. Explain network covalent (giant) structure, with reference to diamond and sand (SiO2).

  4. Describe a crystal as a regular arrangement of particles (atoms, ions or molecules).

  5. Define an amorphous material and a fiber structure.

  • Amorphous materials: no regular structures or crystal. Short range order may occur as far as next neighbor atoms. The general appearance of amorphous materials is glossy and they can occur in ceramics, polymers and metals.

  • Fibers: length-to-thickness ratio of at least 80 but are generally much longer. Textile fibers and food are made up of polymers.

  1. Explain melting in terms of the behavior of particles and the bonding.

  2. Explain boiling in terms of the behavior of particles and the bonding.

  3. Discuss the significance of pure substances melting at a fixed temperature, and mixtures softening over a range of temperatures before melting.


The IB Properties/Bonding Matrix

  1. Describe the relative values of the materials in the IB properties/bonding matrix in terms of their bonding.

  2. Analyze data related to the IB properties/bonding matrix.

  3. Evaluate the importance of the IB properties/bonding matrix in a given design context.


The Properties of Metals and Alloys

  1. State that metals (pure or alloyed) exist as crystals.

  2. Draw and describe what is meant by grain size.

  3. Explain how grain size can be controlled and modified

  • rate of cooling of molten metal: Alters grain size and formation of various phases within the metal. Slow cooling allows larger grains to form; rapid cooling produces smaller grains.

  • heat treatment after solidification: allows material to diffuse between neighboring grains and the grain structure to change. Directional properties in the structure may be achieved by selectively cooling one area of the solid.

  1. Explain in words and diagrams how metals work harden after being plastically deformed.

  2. Explain in words and diagrams the effect of alloying on malleability and ductility.


The Properties of Thermoplastics and Thermosets

  1. Draw and describe the structure and bonding of a thermoplastic.

  2. Explain the effect of load on a thermoplastic, with reference to orientation of chains.

  3. Explain the reversible effect of temperature on a thermoplastic, with reference to orientation of chains.

  4. Draw and describe the structure and bonding of a thermoset.

  5. Explain the non-reversible effect of temperature on a thermoset.

  6. Discuss the properties and uses of two thermoplastics including polypropene.

  7. Discuss the properties and uses of two thermosets including polyurethane.

  8. Discuss the importance of the properties of plastics on the recycling of plastics.

  9. Evaluate the importance of the properties of thermoplastics and thermosets on product design.


The Properties of Composite Materials

  1. State that composites are a combination of two or more materials which are bonded together to improve their mechanical, physical, chemical or electrical properties.

  2. Describe the structure of wood as a natural composite material.

  • Cellulose fibers in a lignin matrix

  1. Discuss in outline the evolution of synthetic composite materials

  • wattle-and-daub

  • mortar

  • papier mâché

  • reinforced concrete glass reinforced plastic (GRP)

  • carbon reinforced plastic (CRP)

  • high temperature superconductors.

  1. Outline the structure of KevlarTM (aramid) fiber.

  2. Outline two examples where KevlarTM fibers twisted into ropes and woven into sheets (mats) are used.

  • Rope—light, non-stretch ropes used in sailing boats.

  • Sheets—sails yachts, bullet resistant vests

  • composite structures with resinmotor racing cars.

  1. Explain why KevlarTM is suited to these applications with reference to its tensile strength, elasticity and water resistance.

  2. Evaluate the importance of the properties of composite materials in a design context.

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