Key Terms

• Absolute temperature

  Temperature measured in Kelvin
• Absolute zero

  The lowest possible temperature theoretically achieveable -273.15 degrees celius or zero Kelvin
• Acceleration

  The stage in mass spectrometry where positive ions are speeded up by an electric field
• Acid rain

  Rain that has been acidified by pollutants such as sulfur dioxide
• Actual yield

  Mass of product obtained in a reaction
• Addition polymer


  Polymer formed when many small unsaturated molecules join together
• Addition reaction


  The adding together of two or more more to form one larger molecule
• Aldehyde

  An organic compound containing the -CHO functional group
• Alkaline earth metal

  An element from group 2 of the periodic table
• Alkane

  A saturated hydrocarbon with the general molecular formula CnH2n+2
• Allotrope

  Allotropes are different forms of the same element that exist in the same physical state. Diamond and graphite are allotropes of carbon
• Alloy

  A mixture of two or more metals or a mixture of metal and a non metal
• Alpha particle

  A particle consisting of two protons and two neutrons ejected from a nucleus
• Amine

  An organic compound that contains nitrogen atom joined to one or more carbon atoms and two or less hydrogen atoms
• Amount of substance

  The number of particles present, symbol n. It is measured in mole, mol
• Anion

  A negatively charged ion attracted to the anode during electrolysis
• Antacid


  A base taken as a medicine to neutralise excess stomach acid
• Aromatic


  Containing one or more benzene rings
• Atom


  The smallest particle of an element that has the properties of that element
• Atom economy

  The proportion of reactants that are converted into useful products rather than waste products
• Atomic number

  The number of protons in the nucleus of an atom, symbol Z
• Atomic radius

  The distance from the centre of the nucleus to the outer electrons of an atom
• Aufbau principle

  The building up process that describes the filling of atomic orbitals in order of increasing energy
• Avogadro constant


  The number of particles in one mole of a substance- 6.022*10^23
• Avogadro's principle

  The idea that equal volumes of gases contain the same number of molecules under the same conditions of temperature and pressure
• Axial atom

  Atom positioned at the top or bottom of a trigonal bipyramidal molecule
• Barometer

  An instrument for measuring atmospheric pressure
• Base peak


  The tallest peak in a mass spectrum
• Batch process

  An industrial process that is started and stopped at intervals. Production of ethanol by fermentation is a batch process
• Bent line

  The shape of a molecule that contains two bonding pairs and two lone pairs of electrons
• Biofuel


  A fuel made from the products of living things
• Bond angle


  The angle between two adjacent bonds on the same atom
• Bond

  Attractive force between two atoms, ions or molecules
• Boyle's law

  The volume of a fixed mass of gas (at a constant temperature) is inversely proportional to its pressure
• Burette


  Labatory apparatus used to add precise volumes of liquid during a titration
• Carbocation

  Ion with a positively charged carbon atom
• Carbonyl

  An organic compound containing the -C+O functional group, found in baldheads and ketones
• Carboxyl

  An organic compound containing the _COOH functional group
• Carboxylic acid


  Organic acids with the general formula RCOOH. Their names end in -oic acid
• Cation

  A positively charged ion, attracted to the cathodde during electrolysis