Page 59 - Curriculum Visions Dynamic Book

CARBON COMPOuNDS: Any compound that includes the element carbon. Carbon compounds are also called organic compounds because they form an essential part of all living organisms.
CARBON CyCLE: The continuous movement of carbon between living things, the soil, the atmosphere, oceans, and rocks, especially those containing coal
and petroleum.
CAST: To pour a liquid metal, glass, or other material into a mould and allow it to cool so that it solidifies and takes on the shape of the mould.
CATALyST: A substance that speeds up
a chemical reaction but itself remains unchanged. For example, platinum is used in a catalytic converter of gases in the exhausts leaving motor vehicles.
CATALyTIC EFFECT: The way a substance helps speed up a reaction even though that substance does not form part of the reaction.
CATHODIC PROTECTION: The technique of protecting a metal object by connecting it to a more easily oxidisable material. The metal object being protected is made into the cathode of a cell. For example, iron can be protected by coupling it with magnesium.
CATION: An ion with a positive charge, often a metal.
CELL: A vessel containing two electrodes and a liquid substance that conducts electricity (an electrolyte).
CELLuLOSE: A form of carbohydrate. See CARBOHyDRATE
CEMENT: A mixture of alumina, silica, lime, iron oxide, and magnesium oxide that is burned together in a kiln and then made into a powder. It is used as the main ingredient of mortar and as the adhesive in concrete.
CERAMIC: A crystalline nonmetal. In a more everyday sense it is a material based on clay that has been heated so that it has chemically hardened.
CHARRING: To burn partly so that some of a material turns to carbon and turns black.
CHINA: A shortened version of the original “Chinese porcelain,” it also refers to various porcelain objects such as plates and vases meant for domestic use.
CHINA CLAy: The mineral kaolinite, which is a very white clay used as the basis of porcelain manufacture.
CLAy MINERALS: The minerals, such as kaolinite, illite, and montmorillonite, that occur naturally in soils and some rocks, and that are all minute platelike crystals.
COkE: A form of coal that has been roasted in the absence of air to remove much of the liquid and gas content.
COLOuRANTS: Any substance that adds a colour to a material. The pigments in
paints and the chemicals that make dyes are colourants.
COLOuRFAST: A dye that will not “run” in water or change colour when it is exposed to sunlight.
COMPOSITE MATERIALS: Materials such as plywood that are normally regarded as a single material, but that themselves are made up of a number of different materials bonded together.
COMPOuND: A chemical consisting of two or more elements chemically bonded together, for example, calcium carbonate.
COMPRESSED AIR: Air that has been squashed to reduce its volume.
COMPRESSION: To be squashed.
COMPRESSION MOuLDING: The shaping of an object, such as a headlight lens, which is achieved by squashing it into a mould.
CONCRETE: A mixture of cement and a coarse material such as sand and small stones.
CONDENSATION: The process of changing a gas to a liquid.
CONDENSATION POLyMERISATION:
The production of a polymer formed by
a chain of reactions in which a water molecule is eliminated as every link of the polymer is formed. Polyester is an example.
CONDuCTION: (i) The exchange of heat (heat conduction) by contact with another object, or (ii) allowing the flow of electrons (electrical conduction).
CONDuCTIVITy: The property of allowing the flow of heat or electricity.
CONDuCTOR: (i) Heat – a material that allows heat to flow in and out of it easily. (ii) Electricity – a material that allows electrons to flow through it easily.
CONTACT ADHESIVE: An adhesive that, when placed on the surface to be joined, sticks as soon as the surfaces are placed firmly together.
CONVECTION: The circulating movement of molecules in a liquid or gas as a result of heating it from below.
CORRODE/CORROSION: A reaction usually between a metal and an acid or alkali in which the metal decomposes. The word is used in the sense of the metal being eaten away and dangerously thinned.
CORROSIVE: Causing corrosion, that is, the oxidation of a metal. For example, sodium hydroxide is corrosive.
COVALENT BONDING: The most common type of strong chemical bond, which occurs when two atoms share electrons. For example, oxygen O2.
CRANkSHAFT: A rodlike piece of a machine designed to change linear into rotational motion or vice versa.
CRIMP: To cause to become wavy. CRuCIBLE: A ceramic-lined container for
holding molten metal, glass, and so on.
CRuDE OIL: A chemical mixture of petroleum liquids. Crude oil forms the raw material for an oil refinery.
CRySTAL: A substance that has grown freely so that it can develop external faces.
CRySTALLINE: A solid in which the atoms, ions, or molecules are organized into an orderly pattern without distinct crystal faces.
CuRING: The process of allowing a chemical change to occur simply by waiting a while. Curing is often a process of reaction with water or with air.
CyLINDER GLASS: An old method of making window glass by blowing a large bubble of glass, then swinging it until it forms a cylinder. The ends of the cylinder are then cut off with shears and the sides of the cylinder allowed to open out until they form a flat sheet.
DECIDuOuS: A plant that sheds its leaves seasonally.
DECOMPOSE: To rot. Decomposing plant matter releases nutrients back to the soil and in this way provides nourishment for a new generation of living things.
DENSITy: The mass per unit volume (for example, g/c3).
DESICCATE: To dry up thoroughly.
DETERGENT: A cleaning agent that is able to turn oils and dirts into an emulsion and then hold them in suspension so they can be washed away.
DIE: A tool for giving metal a required shape either by striking the object with the die or by forcing the object over or through the die.
DIFFuSION: The slow mixing of one substance with another until the two substances are evenly mixed. Mixing occurs because of differences in concentration within the mixture. Diffusion works rapidly with gases, very slowly with liquids.
DILuTE: To add more of a solvent to a solution.
DISSOCIATE: To break up. When a compound dissociates, its molecules break up into separate ions.
DISSOLVED: To break down a substance in a solution without causing a reaction.
DISTILLATION: The process of separating mixtures by condensing the vapours through cooling. The simplest form
of distillation uses a Liebig condenser arranged with just a slight slope down
to the collecting vessel. When the liquid mixture is heated and vapours are produced, they enter the water cooled condenser and then flow down the tube, where they can be collected.
DISTILLED WATER: Water that has its dissolved solids removed by the process of distillation.
DOPING: Adding an impurity to the surface of a substance in order to change its properties.
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