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34 Cards in this Set
- Front
- Back
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Malleable
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bonds allow metal to stay together when bent or struck
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Ductile
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ability to be drawn (stretched into wires)
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What makes metals electrical conductors?
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They have free outer shell electrons, which enables the carrying of electrical currents.
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Why are few metals used in their pure form?
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They are generally too soft to be made into anything useful.
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What is an alloy?
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A combination of one or more metal elements.
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How many carats is pure gold?
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24
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What metals are found in the earth's crust?
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Aluminium, iron, calcium, magnesium, sodium, potassium.
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What are native elements?
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Elements that can be found in nature uncombined with other elements.
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What are minerals?
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Rocks containing large amounts of a particular metal.
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What is an ore?
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A mineral with enough metal to mine.
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What causes metals to rust?
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Air and water.
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What is rust?
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Iron (III) oxide. It is a result of a reaction between water, oxygen and a metal.
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What accelerates the rusting process?
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Salt and heat.
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What is galvanised iron?
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Iron that has been covered with a layer of zinc.
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What is sacrificial protection?
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When a metal is covered with a layer of a more reactive metal, the outer layer will react instead of the core metal.
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Are plastics insulators or conductors?
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Insulators - no free electrons
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Plastics are not..
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biodegradable
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What is polymerisation?
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Combining molecules derived from the oil industry to create plastic.
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What is a thermoplastic?
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A remouldable plastic consisting of long polymer chains.
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What are thermoplastics manufactured as?
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Powder, pellets or granules for shipping to factories.
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Are thermoplastics recyclable?
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Yes
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What is a thermosetting plastic?
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Plastics with a rigid polymer structure.
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What are 3 properties of thermosetting plastics?
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They are hard (scratch resistant), brittle (will shatter when dropped) and rigid (not able to be bent).
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What happens when you heat a thermoplastic?
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It softens and is able to be moulded.
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What happens when you heat a thermosetting plastic?
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The bonds will break and the plastic decomposes (chars).
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What is a monomer?
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A small molecule derived from crude oil.
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What is a polymer?
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A group of monomers joined through the process of polymerisation.
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What is a fibre?
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Any substance that can be woven or knitted into a fabric.
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What are the two main types of fibre?
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Natural and synthetic.
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What are synthetic fibres made from?
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Chemicals and polymers.
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Which type of fibre is stronger?
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Synthetic fibres.
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What is extrusion moulding?
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Pellets of plastic are poured into a machine which melts it and puts it through a nozzle, which creates the shape.
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What is injection moulding?
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Pellets are put through and pushed through the machine. It is melted and injected into a mould.
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What is blow moulding?
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Softened plastic is dropped into mould. Metal tube blows compressed air into it, to make it hollow.
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