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155 Cards in this Set
- Front
- Back
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Acid
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When dissolved in water, its solution has a pH number less than 7. Acids are proton (H+ ion) donors. |
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Activation energy |
The minimum energy needed to start off a reaction. |
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Alkali |
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Alkali metal |
Elements in group 1 of the periodic table, e.g. lithium (Li), sodium (Na), potassium (K) |
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Alkane |
Saturated hydrocarbon with the general formula CnH2n+2, e.g. methane, ethane, propane. |
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Alkene |
Unsaturated hydrocarbon which contains a carbon - carbon double bond. The general formula is CnH2n, e.g. ethane C2H4 |
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Alloy
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A mixture of metals (sometimes with non-metals). e.g. brass is a mixture copper and zinc.
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Aluminium |
A low density, corrosion resistant metal used in many alloys, including those used in aircraft industry. |
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Amphoteric oxides
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These oxides behave like both acids and bases. e.g. aluminium oxide |
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Anode |
The positive electrode in an electrolysis cell. |
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Anhydrous |
Describes a substance that does not contain water. |
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Aqueous solution |
The mixture made by adding a soluble substance to water.
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Atmosphere |
The relatively thin layer of gases that surround planet earth |
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Atom |
The smallest part of an element that can still be recognised as that element. |
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Atomic number |
The number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number. |
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Base |
The oxide, hydroxide or carbonate of a metal that will react with an acid, forming a salt as one of the products. (If a base dissolves in water it is called an alkali). Bases are proton (H+ ion) acceptors. |
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Biodegradable |
Materials that can be broken down by microorganisms. |
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Biodiesel |
Fuel for cars made from plant oils.
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Biofuel |
Fuel made from animal or plant products |
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Bioleaching |
Process of extraction of metals from ores using microorganisms. |
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Blast furnace |
The huge reaction vessels used in industry to extract iron from its ore |
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Bond energy |
The energy needed to break a particular chemical bond.
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Burette |
A long glass tube with a tap at one end and markings to show volumes of liquid, used to add precisely known amounts of liquids to a solution in a conical flask below it. |
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Calcium carbonate
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the main compound found in limestone. It is a white solid whose formula is CaCO3. |
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Carbon monoxide |
A toxic gas with the formula CO |
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Cast iron |
The impure iron taken directly from the blast furnace.
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Catalyst |
A substance that speeds up a chemical reaction. At the end of the reaction the catalyst remains chemically unchanged. |
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Cathode |
the negative electrode in an electrolysis cell |
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Cement |
a building material made by heating limestone and clay |
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Chromatography |
The process whereby small amounts of dissolved substances are separated by running a solvent along a material such as absorbent paper. |
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Closed system |
A system in which no matter or energy enters or leaves. |
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Collision theory |
An explanation of chemical reactions in terms of reacting particles colliding with sufficient energy for a reaction to take place. |
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Compound
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A substance made when two or more elements are chemically bonded together. For example, water (H2O) is a compound of hydrogen and oxygen |
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Copper-rich ore
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Rock that contains a high proportion of a copper compound. |
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Covalent bonding
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The attraction between two atoms that share one or more pairs of electrons |
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Cracking |
The reaction used in the oil industry to break down large hydrocarbons into smaller, more useful ones. This occurs when the hydrocarbon vapour is either passed over a hot catalyst or mixed with steam and heated to a high temperature.
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Crystallisation |
A technique used to separate a dissolved crystalline solid from its solution |
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Delocalised electron |
Bonding electron that is no longer associated with any one particular atom. |
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Desalination |
The removal of salts from water (usually seawater) to make it suitable for drinking and other uses.
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Diffusion
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The process whereby the particles liquids or gases mix with each other due to the random motion of the particles. |
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Displace |
When one element takes the place of another in a compound. for example iron + copper sulphate --> iron sulphate + copper |
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Distillation
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Separation of a liquid from a mixture by evaporation followed by condensation. |
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Dot-and-cross diagram |
A drawing to show the arrangement of the outer shell electrons only of the atoms or ions in a substance.
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Double bond |
A covalent bond made by sharing two pairs of electrons. |
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electrolysis
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The breakdown of a substance containing ions by electricity |
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Electrolyte
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A liquid, containing free moving ions, that is broken down by electricity in the process of electrolysis. |
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Electron |
A tiny particle with a negative charge. Electrons orbit the nucleus in atoms or ions
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Electronic structure |
A set of numbers to show the arrangement of electrons in their shells (or energy levels), for example, the electronic structure of a potassium atom is 2,8,8,1 |
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Element |
A substance made up of only one type of atom. An element cannot be broken down chemically into any simpler substance. |
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Empirical formula
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The simplest ratio of elements in a compound |
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end point |
the point in a titration where the reaction is complete and the titration should stop. |
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Endothermic |
A reaction that takes in energy from the surroundings |
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Energy level |
same as a shell |
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Equilibrium
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The point in a reversible reaction in which the forward and backward rates of reaction are the same. Therefore, the amounts of substances present in the reacting mixture remain constant. |
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Ethene |
An alkene with the formula C2H4 |
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Exothermic
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a reaction that gives out energy to the surroundings |
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Fermentation |
The reaction in which the enzymes in yeast turn glucose into ethanol and carbon dioxide |
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Filtration |
The technique used to separate substances that are insoluble in a particular solvent from those that are soluble. |
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Flammable |
Easily ignited and capable of burning rapidly |
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Flouridation
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the addition of fluoride to drinking water supplies to help prevent tooth decay. |
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Fraction |
Hydrocarbons with similar boiling points separated from crude oil. |
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Fractional distillation
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A way to separate liquids from a mixture of liquids by boiling off the substances at different temperatures, then condensing and collecting the liquids. |
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Fullerene |
Form of the element carbon that can form a large cage-like structure, based on hexagonal rings of carbon atoms. |
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Functional group |
An atom or group of atoms that give organic compounds their characteristic reations |
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Gas
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the state of matter in which there are large spaces, on average, between particles that are moving randomly at high speeds. |
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Gas chromatography |
The process of separating the components in a mixture by passing the vapours through a column and detecting them as they leave the column at different times. |
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Giant covalent structure
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A huge 3-D network of covalently bonded atoms (e.g. the giant lattice of carbon atoms in diamond or graphite) |
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Giant lattice |
A huge 3-D network of atoms or ions (e.g. the giant ionic lattice of sodium chloride) |
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Giant structure
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Same as giant lattice |
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Global dimming
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the reflection of sunlight by tiny solid particles in the air. |
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Global warming
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The increasing average temperature of the earth. |
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Gradient |
Change of the quantity plotted on the y-axis divided by the change of the quantity plotted on the x-axis. |
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Group |
All the elements in each column (labelled 1 to 7 and 0) down the periodic table |
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Half equation |
E.g. Na+ + e- --> Na |
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Halides |
Salts containing ions of the group 7 elements. |
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Halogens |
The elements found in group 7 of the periodic table. |
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Homologous series |
a group of related organic compounds that have the same functional group, e.g. the molecules of the homologous series of alcohols all contain the -OH group |
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Hydrated
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describes a substance that contains water in its crystals e.g. hydrated copper sulphate |
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Hydrocarbon |
A compound containing only hydrogen and carbon |
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Incomplete combustion |
When a fuel burns in insufficient oxygen, producing carbon monoxide as a toxic product. |
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inert |
unreactive |
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Intermolecular force |
the attraction between the individual molecules in a covalently bonded substance. |
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Ion
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A charged particle produced by the loss or gain of electrons from an atom |
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ionic equation
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An equation that shows only ions or atoms that change in a chemical reaction |
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Ion-exchange column
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A water softener that works by replacing calcium and magnesium ions with sodium and hydrogen ions, removing the hardness. |
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Ionic bonding
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The electrostatic force of attraction between positively and negatively charged ions. |
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Isotopes
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Atoms that have the same number of protons but different numbers of neutrons, i.e. they have the same atomic number but different mass numbers. |
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Lattice |
A giant three-dimensional network of particles
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Limewater |
The common name for calcium hydroxide solution |
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Liquid |
The state of matter in which the particles are touching but can slip and slide over and around each other in random motion. |
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Macromolecule |
Giant covalent structure. |
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Mass number |
The number of protons plus the number of neutrons in the nucleus of an atom |
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Mass spectrometer |
A machine that can be used to analyse small amounts of a substance to identify it and to find its relative molecular mass. |
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Mixture |
When some elements or compounds are mixed together and intermingle but do not react together (i.e. no new substance is made). A mixture is not a pure substance. |
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Mole
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The amount of substance in the relative atomic mass or formula mass of a substance in grams |
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Molecular formula
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The chemical formula that shows the actual numbers of atoms in a particular molecule (e.g. C2H4) |
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Molecular ion peak
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The peak on the mass spectrum of a substance which tells us the relative molecular mass of the substance. The peak is produced by the heaviest positive ion shown on the mass spectrum |
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Monomers
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Small reactive molecules that react together in repeating sequences to form a very large molecule (a polymer) |
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Nanoscience
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The study of very tiny particles or structures between 1 and 100 nanometres in size |
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Neutral
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A solution with a pH value of 7 that is neither acidic nor alkaline. Alternatively, something that carries no electrical charge - neither positively nor negatively charged. |
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Neutralisation |
The chemical reaction of an acid with a base forming a salt and water. If the base is a carbonate or hydrogen carbonate, carbon dioxide is also produced in the reaction. |
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Neutron |
A dense particle found in the nucleus of an atom. It is electrically neutral, carrying no charge. |
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Nitrogen oxides |
Gaseous pollutants given off from motor vehicles; a cause of acid rain. |
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Noble gases |
The very unreactive elements found in group 0 of the periodic table. |
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Nucleus |
The very small and dense central part of an atom which contains protons and neutrons. |
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Ore |
Rock which contains enough metal to make it economically worth while to extract the metal. |
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Oxidation |
The reaction when oxygen is added to a substance (or when electrons are lost from a substance)
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Oxidised |
A reaction where oxygen is added to a substance (or when electrons are lost from a substance) |
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Particulate |
Small solid particle given off from motor vehicles as a result of incomplete combustion of its fuel. |
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Percentage yield
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The actual mass of product collected in a reaction divided by the maximum mass that could have been formed in theory, multiplied by 100. |
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Periodic table |
An arrangement of elements in order of their atomic numbers, forming groups and periods. |
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pH scale |
A scale of numbers (1-14) that shows how strongly acidic or alkaline a solution is. Acids have a pH value less that 7. Alkalis have a pH value above 7. A neutral liquid has a pH value of 7. |
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Phytomining
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The process of extraction of metals from ores using plants. |
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Pipette
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A glass tube used to measure accurate volumes of liquids. |
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Polymer |
Very large molecules made up of many repeating units, for example poly(ethene) |
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Polymerisation |
The reaction of monomers to make a polymer |
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Precipitate |
An insoluble solid formed by a reaction taking place in solution |
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Product |
A substance made as a result of a chemical reaction |
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Propene |
An alkene with the formula C3H6 |
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Proton
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A tiny positive particle found inside the nucleus of an atom. |
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Reactant |
A substance we start with before a chemical reaction takes place. |
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Reactivity series
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A list of elements in order of their reactivity. The most reactive element is put at the top of the list. |
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Reduction |
A reaction in which oxygen is removed (or electrons are gained) |
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Relative atomic mass
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The average mass of the atoms of an element compared with carbon-12 (which is given a mass of exactly 12). The average mass must take into account the proportions of the naturally occurring isotopes of the element.
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Relative formula mass
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The total of the relative atomic masses, added up in the ratio shown in the chemical formula, of a substance. |
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Retention factor |
On a paper chromatogram, this is a ratio, calculated by dividing the distance a spot travels up the paper by the distance the solvent front travels. |
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Retention time |
The time it takes a component in a mixture to pass through the column during gas chromatography.
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Reversible reaction
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A reaction in which the products can re-form the reactants |
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Rusting |
The corrosion of iron by reaction with oxygen and water to form rust (hydrated copper(III) oxide) |
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Sacrificial protection |
A method of protection against rusting by connecting to, or adding a thin coating of, a metal which is more reactive than iron, such as zinc or magnesium. |
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Salt |
A salt is a compound formed when some or all of the hydrogen in an acid is replaced by a metal (or by an ammonium ion). For example, potassium nitrate, KNO3 (from nitric acid) |
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Saturated hydrocarbon |
Describes a hydrocarbon that contains as many hydrogen atoms as possible in each molecule. |
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Shape memory alloy |
Mixture of metals which respond to changes in temperature. |
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Shell (or energy level) |
An area in an atom, around its nucleus, where the electrons are found. |
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Smart polymer
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Polymers that change shape in response to changes in their environment. |
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Smelting |
Heating a metal ore in order to extract its metal. |
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Solid |
The state of matter in which the particles are tightly packed together and vibrate about fixed positions. |
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Stainless steel |
A chromium-nickel alloy of steel which does not rust |
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State symbol |
The abbreviations used in balanced symbol equations to show if the reactants and products are solid (s), liquid (l), gas (g) or dissolved in water (aq) |
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States of matter |
Solid, liquid and gas are three states of matter. |
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Steel |
an alloy of iron with small amounts of carbon and other metals, such as nickel and chromium, added. |
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Strong acids |
Acid that ionise completely in aqueous solutions.
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Sulphur dioxide
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A toxic gas whose formula is SO2. it caused acid rain. |
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Thermal decomposition |
The breakdown of a compound by heat. |
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Thermosetting polymer |
Polymer that can form extensive cross-linking between chains, resulting in rigid materials which are heat-resistant. |
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Thermosoftening polymer |
Polymer that forms plastics which can be softened by heat, then remoulded into different shapes as they cool down and set.
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Titanium
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A shiny, corrosion-resistant metal used to make alloys. |
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Titration |
A method used for measuring the volumes of two solutions that react together |
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Transition element |
Element from the central block of the periodic table. It has typical metallic properties and forms a coloured compound. |
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Transition metal
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Same as transition element. |
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Universal indicatior
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A mixture of indicators which can change through a range of colours depending on the pH of a solution. Its colour is matched to a pH number using a pH scale. It shows how strongly acidic or alkaline liquids and solutions are. |
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Unsaturated hydrocarbon |
A hydrocarbon whose molecules contain at least one carbon-carbon double bond. |
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Viscosity |
The resistance of a thick liquid to flowing or the "thickness" or resistance of a liquid to pouring. |
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Weak acids |
Acids that do not ionise completely in aqueous solutions. |
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Yield |
same as percentage yield
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