Chemistry - an illustrated guide to science (794128), страница 37
Текст из файла (страница 37)
Oxides can be either ionic or covalent.oxidizing agent A substance that can cause the oxidationof another substance by being reduced itself.oxygen (O) A colorless, odorless gaseous element. It themost common element in Earth’s crust and is the basis forrespiration in plants and animals..ozone (O3) One of the two allotropes of oxygen. A bluishgas with a penetrating smell, it is a strong oxidizing agent.period The horizontal rows of elements in the periodictable.periodic table A table of elements, arranged in ascendingorder of atomic number, that summarizes the majorproperties of the elements.periodicity Recurring at regular intervals.peroxide A compound that contains the peroxide ion O22–.Peroxides are strong oxidizing agents.pH A scale from 0 to 14 that measures the acidity or alkalinityof a solution. A neutral solution has a pH of 7, while an acidicsolution has a lower value and an alkaline solution a highervalue.pH meter A device that uses an electrochemical cell tomeasure pH.phosphorescence The emission of light by an object, andthe persistence of this emission over long periods, followingirradiation by light or other forms of radiation.photochemical reaction A chemical reaction that isinitiated by a particular wavelength of light.photoelectric effect The emission of electrons frommetals upon the absorption of electromagnetic radiation.photosynthesis The photochemical reaction by whichgreen plants make carbohydrates using carbon dioxide andwater.platinum (Pt) A soft, shiny, silver metallic transitionelement that is malleable and ductile.pollutant A substance that harms the environment when itmixes with air, soil, or water.polyethene A thermoplastic polymer made by additionpolymerization of ethene.polymer A material containing very large molecules built upfrom a series of repeated small basic units (monomers).polymerization The building up of long chainhydrocarbons from smaller ones.polysaccharide A organic polymer composed of manysimple sugars (monosaccharides).precipitate An insoluble substance formed by a chemicalreaction.product A substance produced during a chemical reaction.protein A large, complex molecule composed of a longchain of amino acids.proton The positively charged particle found in the nucleusof the atom.protostar The early stage in a star’s formation before theonset of nuclear burning.quantum number The number used when describing theenergy levels available to atoms and molecules.racemate A mixture of equal amounts of left- and righthanded stereoisomers of a chiral molecule.radiation Energy that is transmitted in the form of particles,rays, or waves.radical A group of atoms forming part of many molecules.radioactive decay The process by which unstableradioactive atoms are transformed into stable, non-radioactiveatoms.radioactivity The spontaneous disintegration of certainisotopes accompanied by the emission of radiation.rate of reaction The speed at which a chemical reactionproceeds.reactant A substance present at the start of a chemicalreaction that takes part in the reaction.reaction A process in which substances react to form newsubstances.reactivity The ability of substances to react to form newsubstances.reactivity series of metals Metallic elements arrangedin order of their decreasing chemical reactivity.reagent A substance that takes part in a chemical reaction,one that is usually used to bring about a chemical change.red giant A very large, cool star in the final stages of its life.redox reaction A process in which one substance isreduced and another is oxidized at the same time.reducing agent A chemical that can reduce another whilebeing oxidized itself.reduction A chemical reaction in which a substance gainselectrons, looses oxygen, or gains hydrogen.
It is the reverseof oxidation.reforming The conversion of straight chain molecules intothose that are branched in order to improve their efficiencies.residfining The process used on the residue fraction ofcrude oil to convert it into a usable product.residue The solid remaining after the completion of achemical process.resonance structure In organic chemistry, a diagrammatictool to symbolize bonds between atoms in molecules.respiration The chemical reaction by which an organismderives energy from food.reverse reaction A reaction in which the products areconverted into reactants.reversible reaction A chemical reaction that can proceedin either direction. It does not reach completion but achievesdynamic equilibrium.Rf value The ratio of the distance moved by a substance in achromatographic separation to the distance moved by thesolvent.rust A reddish-brown oxide coating on iron or steel causedby the action of oxygen and water.salt A compound formed from an acid in which all or part ofthe hydrogen atoms are replaced by a metal or metal-likegroup.
Salts are generally crystalline.saponification The treatment of an ester (hydrolysis) witha strong alkaline solution to form a salt of a carboxylic acidand an alcohol.© Diagram Visual Information Ltd.KEY WORDS20 4KEY WORDS© Diagram Visual Information Ltd.saturated A solution where there is an equilibrium betweenthe solution and its solute.scandium (Sc) Silvery-white metallic element in thelanthanide series found in nature only in minute quantities.sewage Wastewater from domestic and industrial sources.shell A group of orbitals at a similar distance from an atomicnucleus.silver (Ag) A white, shiny, ductile metallic element.silver nitrate (AgNO3) A very soluble white salt thatdecomposes to form silver, oxygen, and nitrogen dioxide onheating.slag Waste material that collects on the surface of a moltenmetal during the process of either extraction or refining.smelting The process of extracting a metal from its ores.soap A cleansing agent made from fatty acids derived fromnatural oils and fats.sodium (Na) A soft, silver-white metallic element.sodium chloride (NaCl) A nonvolatile ionic compoundthat is soluble in water.sodium hydroxide (NaOH) A white, translucent,crystalline solid that forms a strongly alkaline solution inwater.sol A liquid solution or suspension of a colloid.solid A state of matter in which the particles are not freeto move but in which they can vibrate about fixedpositions.solubility A measure of the quantity of a solute that willdissolve in a certain amount of solvent to form a saturatedsolution under certain conditions of temperature andpressure.solubility curve A graphic representation of the changingsolubility of a solute in a solvent at different temperatures.soluble A relative term that describes a substance that candissolve in a particular solvent.solute A substance that dissolves in a solvent and thus formsa solution.solution A uniform mixture of one or more solutes in asolvent.solvent A substance, usually a liquid, in which a solutedissolves to form a solution.species The common name for entities (atoms, molecules,molecular fragments, and ions) being subjected toinvestigation.spectrum The arrangement of electromagnetic radiationinto its constituent wavelengths.starch A polysaccharide with the formula (C6 H10 O5) .
It iscomposed of many molecules of glucose.stationary phase That which the mobile phase moves on.In paper chromatography it is the paper.stoichiometry The calculation of the quantities of reactantsand products involved in a chemical reaction.subatomic particles The particles from which atoms aremade. Neutrons and protons are found in the nucleus of theatom. Electrons form a cloud around the nucleus.sucrose A disaccharide sugar that occurs naturally in mostplants.sulfate A salt or ester of sulfuric acid.sulfide A compound of sulfur and a more electropositiveelement.sulfur (S) A yellow, non-metallic element that is foundabundantly in nature.sulfuric acid (H2 SO4 ) An oily, colorless, odorless liquidthat is extremely corrosive.sulfur dioxide (SO2 ) A colorless gas with a pungent odorof burning sulfur.
It is very soluble in water.sulfur trioxide (SO3) A white, soluble solid that fumes inmoist air. It reacts violently with water to form sulfuric acid.supernova The explosion caused when a massive star diesand collapses.surface area The sum of the area of the faces of a solid.suspension A type of dispersion. Small solid particles aredispersed in a liquid or gas.tensile strength The amount of stress a material can standwithout breaking.thorium Th.
A gray, radioactive metallic element used as fuelin nuclear reactors.thorium series One of the naturally occurring radioactiveseries.titanium (Ti) A lightweight, gray metallic element that isvery strong and resistant to corrosion.titration In analytical chemistry, A technique used todetermine the concentration of a solute in a solution.transition metals Metallic elements that have anincomplete inner electron structure and exhibit variablevalencies.triple bond A covalent bond formed between two atoms inwhich three pairs of electrons contribute to the bond.ultraviolet Electromagnetic radiation of shorterwavelengths than visible light, but of longer wavelength thanX rays.unit cell The smallest repeating array of atoms, ions, ormolecules in a crystal.universal indicator A mixture of substances that shows agradual color change over a wide range of pH values.uranium (U) A hard, white, radioactive metallic elementused in nuclear reactors and nuclear weapons.uranium series One of the naturally occurring radioactiveseries.valency The measure of an element’s ability to combinewith other elements.vanadium (V) A silvery-white or gray metallic element usedas a steel additive and in catalysts.van der Waals forces Weak intermolecular or interatomicforces between neutral molecules or atoms.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
