Page 58 - Curriculum Visions Dynamic Book

Set Glossary
ACID RAIN: Rain that falls after having been contaminated by acid gases produced by power stations, vehicle exhausts, and other man-made sources.
ACIDITy: The tendency of a liquid to behave like an acid, reacting with metals and alkalis.
ADDITION POLyMERISATION: The building blocks of many plastics (or polymers) are simple molecules called monomers. Monomers can be converted into polymers by making the monomers link to one another to form long chains in head-to-tail fashion. This is called addition polymerisation or chain polymerisation. It is most often used to link vinyl monomers to produce, for example, PVC, or polyvinyl chloride polymer.
See also CONDENSATION POLyMERISATION
ADHESIVE: Any substance that can hold materials together simply by using some kind of surface attachment. In some cases this is a chemical reaction; in other cases it is a physical attraction between molecules of the adhesive and molecules of the substance it sticks to.
ADOBE: Simple unbaked brick made with mud, straw, and dung. It is dried in the open air. In this form it is very vulnerable to the effects of rainfall and so is most often found in desert areas or alternatively is protected by some waterproof covering, for example, thatch, straw, or reeds.
ALkALI: A base, or substance that can neutralise acids. In glassmaking an alkali is usually potassium carbonate and used as a flux to lower the melting point of the silica.
ALkyD: Any kind of synthetic resin used for protective coatings such as paint.
ALLOy: A metal mixture made up of two or more elements. Most of the elements used to make an alloy are metals. For example, brass is an alloy of copper and zinc, but carbon is an exception and used to make steel from iron.
AMALGAM: An alloy of mercury and one or more other metals. Dentist’s filling amalgam traditionally contains mercury, silver, and tin.
AMPHIBIOuS: Adapted to function on both water and land.
AMORPHOuS: Shapeless and having no crystalline form. Glass is an amorphous solid.
ANION: An ion with a negative charge.
ANNEALING: A way of making a metal, alloy, or glass less brittle and more easy to work (more ductile) by heating it to
a certain temperature (depending on the metal), holding it at that temperature
for a certain time, and then cooling to room temperature.
ANODIzING: A method of plating metal by electrically depositing an oxide film onto the surface of a metal. The main purpose is to reduce corrosion.
ANTICyCLONE: A region of the Earth’s atmosphere where the pressure is greater than average.
AquEOuS SOLuTION: A substance dissolved in water.
ARTIFACT: An object of a previous time that was created by humans.
ARTIFICIAL DyE: A dye made from
a chemical reaction that does not occur in nature. Dyes made from petroleum products are artificial dyes.
ARTIFICIAL FIBRE: A fibre made from a material that has been manufactured, and that does not occur naturally. Rayon is an example of an artificial fibre.
Compare to SyNTHETIC ATMOSPHERE: The envelope of gases
that surrounds the Earth.
ATOM: The smallest particle of an element; a nucleus and its surrounding electrons.
AzO: A chemical compound that contains two nitrogen atoms joined by a double bond and each linked to a carbon atom. Azon compounds make up more than half of all dyes.
BARk: The exterior protective sheath of the stem and root of a woody plant such as a tree or a shrub. Everything beyond the cambium layer.
BAROMETER: An instrument for measuring atmospheric pressure.
BASE METAL: Having a low value and poorer properties than some other metals. Used, for example, when describing
coins that contain metals other than gold or silver.
BAST FIBRES: A strong woody fibre that comes from the phloem of plants and is used for rope and similar products. Flax is an example of a bast fibre.
BATCH: A mixture of raw materials or products that are processes in a tank or kiln. This process produces small amounts of material or products and can be contrasted to continuous processes. Batch processing is used to make metals, alloys, glass, plastics, bricks, and other ceramics, dyes, and adhesives.
BAuxITE: A hydrated impure oxide of aluminium. It is the main ore used to obtain aluminium metal. The reddish- brown colour of bauxite is caused by impurities of iron oxides.
BINDER: A substance used to make sure the pigment in a paint sticks to the surface it is applied to.
BIOCERAMICS: Ceramic materials that are used for medical and dental purposes, mainly as implants and replacements.
BLAST FuRNACE: A tall furnace charged with a mixture of iron ore, coke, and limestone and used for the refining (smelting) of iron ore. The name comes from the strong blast of air used during smelting.
BLOWING: Forming a glass object by blowing into a gob of molten glass to form a bubble on the end of a blowpipe.
BOLL: The part of the cotton seed that contains the cotton fibre.
BOILING POINT: The temperature at which a liquid changes to a vapour. Boiling points change with atmospheric pressure.
BOND: A transfer or a sharing of electrons by two or more atoms. There are a number of kinds of chemical bonds, some very strong, such as covalent bonding and ionic bonding, and others quite weak, as in hydrogen bonding. Chemical bonds form because the linked molecules are more stable than the unlinked atoms from which they are formed.
BOyLE’S LAW: At constant temperature and for a given mass of gas the volume of the gas is inversely proportional to the pressure that builds up.
BRITTLE: Something that has almost no plasticity and so shatters rather than bends when a force is applied.
BuLL’S EyE: A piece of glass with concentric rings marking the place where the blowpipe was attached to the glass. It is the central part of a pane of crown glass.
BuOyANCy: The tendency of an object to float if it is less dense than the liquid it is placed in.
BuRN: A combustion reaction in which a flame is produced. A flame occurs where gases combust and release heat and light. At least two gases are therefore required if there is to be a flame.
CALORIFIC: Relating to the production of heat.
CAMBIuM: A thin growing layer that separates the xylem and phloem in most plants, and that produces new cell layers.
CAPACITOR: An electronic device designed for the temporary storage of electricity.
CAPILLARy ACTION,
CAPILLARITy: The process by which surface tension forces can draw a liquid up a fine-bore tube.
CARBOHyDRATES: One of the main constituents of green plants, containing compounds of carbon, hydrogen, and oxygen. The main kinds of carbohydrate are sugars, starches, and celluloses.
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