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A.1 Classification of materials
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Understandings:
Materials are classified based on their uses, properties, or bonding and structure. Applications and skills: Evaluation of various ways of classifying materials. |
Bonding and properties of metals
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This video covers the bonding, structure, and properties of metals.
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A.1 Properties of materials
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Applications and skills:
Relating physical characteristics (melting point, permeability, conductivity, elasticity, brittleness) of a material to its bonding and structures (packing arrangements, electron mobility, ability of atoms to slide relative to one another). |
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This video covers the structure and bonding of ionic compounds in more detail.
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This video covers the structure and bonding of covalent compounds in more detail.
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A.1 Bonding triangle diagrams
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Understandings:
The properties of a material based on the degree of covalent, ionic or metallic character in a compound can be deduced from its position on a bonding triangle. Applications and skills: Use of bond triangle diagrams for binary compounds from electronegativity data. Guidance: See section 29 of the data booklet for a triangular bonding diagram. |
A.2 Extraction of metals
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Understandings:
Reduction by coke (carbon), a more reactive metal, or electrolysis are means of obtaining some metals from their ores. Applications and skills: Deduction of redox equations for the reduction of metals. Relating the method of extraction to the position of a metal on the activity series. |
A.2 Extraction of aluminium
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Applications and skills:
Explanation of the production of aluminium by the electrolysis of alumina in molten cryolite. |
A.2 Faraday constant
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Understandings:
The relationship between charge and the number of moles of electrons is given by Faraday’s constant, F. Applications and skills: Solving stoichiometric problems using Faraday’s constant based on mass deposits in electrolysis. |
A.2 Alloys
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Understandings:
Alloys are homogeneous mixtures of metals with other metals or non-metals. Applications and skills: Explanation of how alloying alters properties of metals. |
A.2 Diamagnetism and paramagnetism
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Understandings:
Diamagnetic and paramagnetic compounds differ in electron spin pairing and their behaviour in magnetic fields. Applications and skills: Discussion of paramagnetism and diamagnetism in relation to electron structure of metals. |
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This video looks at the magnetism of the transition metals.
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A.2 Inductively coupled plasma mass spectrometry (SL)
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Guidance:
Details of operating parts of ICP-MS and ICP-OES instruments will not be assessed. Only analysis of metals should be covered. The importance of calibration should be covered. |
Understandings:
Trace amounts of metals can be identified and quantified by ionizing them with argon gas plasma in Inductively Coupled Plasma (ICP) Spectroscopy using Mass Spectroscopy ICP-MS and Optical Emission Spectroscopy ICP-OES. Applications and skills: Explanation of the plasma state and its production in ICP- MS/OES. Identify metals and abundances from simple data and calibration curves provided from ICP-MS and ICP-OES. Explanation of the separation and quantification of metallic ions by MS and OES. Uses of ICP-MS and ICP-OES. |
6.1 Catalysts
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This video is a review of catalysts from topic 6.
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A.3 Catalysts
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Understandings:
Reactants adsorb onto heterogeneous catalysts at active sites and the products desorb. Homogeneous catalysts chemically combine with the reactants to form a temporary activated complex or a reaction intermediate. Applications and skills: Description of how metals work as heterogeneous catalysts. |
A.3 Transition metal catalysts
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Understandings:
Transition metal catalytic properties depend on the adsorption/absorption properties of the metal and the variable oxidation states. Applications and skills: Description of how metals work as heterogeneous catalysts. |
A.3 Factors that affect the choice of catalyst
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Applications and skills:
Explanation of factors involved in choosing a catalyst for a process. Guidance: Consider catalytic properties such as selectivity for only the desired product, efficiency, ability to work in mild/severe conditions, environmental impact and impurities. |
A.3 Zeolites and nanocatalysts
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Understandings:
Zeolites act as selective catalysts because of their cage structure. Catalytic particles are nearly always nanoparticles that have large surface areas per unit mass. Applications and skills: Description of the benefits of nanocatalysts in industry. Guidance: The use of carbon nanocatalysts should be covered. |
A.5 Thermoplastic and thermosetting polymers
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Understandings:
Thermoplastics soften when heated and harden when cooled. A thermosetting polymer is a prepolymer in a soft solid or viscous state that changes irreversibly into a hardened thermoset by curing. Applications and skills: Description of how the properties of polymers depend on their structural features. |
A.5 Elastomers
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Understandings:
Elastomers are flexible and can be deformed under force but will return to nearly their original shape once the stress is released. |
A.5 LDPE and HDPE
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Understandings:
High density polyethene (HDPE) has no branching allowing chains to be packed together. Low density polyethene (LDPE) has some branching and is more flexible. |
A.5 Plasticizers and PVC
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Understandings:
Plasticizers added to a polymer increase the flexibility by weakening the intermolecular forces between the polymer chains. Applications and skills: Description of the use of plasticizers in polyvinyl chloride. Guidance: Consider phthalate esters as examples of plasticizers. |
A.5 Polystyrene
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Applications and skills:
Description of the use of volatile hydrocarbons in the formation of expanded polystyrene. Guidance: Consider only polystyrene foams as examples of polymer property manipulation. |
A.5 Butyl rubber
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Applications and skills:
Deduction of structures of polymers formed from polymerizing 2- methylpropene. |
A.5 Isotactic and atactic polymers
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Understandings:
Isotactic addition polymers have substituents on the same side. Atactic addition polymers have the substituents randomly placed. |
A.7 Disposal of plastics
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Understandings:
Plastics do not degrade easily because of their strong covalent bonds. Burning of polyvinyl chloride releases dioxins, HCl gas and incomplete hydrocarbon combustion products. |
A.7 Dioxins and dioxin-like compounds
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Understandings:
Dioxins contain unsaturated six-member heterocyclic rings with two oxygen atoms, usually in positions 1 and 4. Chlorinated dioxins are hormone disrupting, leading to cellular and genetic damage. Applications and skills: Comparison of the structures of polychlorinated biphenyls (PCBs) and dioxins. Guidance: Dioxins do not decompose in the environment and can be passed on in the food chain. Consider polychlorinated dibenzodioxins (PCDD) and PCBs as examples of carcinogenic chlorinated dioxins or dioxin-like substances. |
A.7 Recycling plastics
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Understandings:
Plastics require more processing to be recycled than other materials. Plastics are recycled based on different resin types. Applications and skills: Discussion of why the recycling of polymers is an energy intensive process. Distinguish possible Resin Identification Codes (RICs) of plastics from an IR spectrum. Guidance: Resin Identification Codes (RICs) are in the data booklet in section 30. |