Chemistry unit 2

• Empirical formula


  A formula which shows the simplest whole number ratio of atoms of each element in a compound
• Molecular formula


  A formula which shows the actual number of atoms of each element in a molecule
• Molar gas volume


  The volume of one mole of gas under specified conditions of temperature and pressure e.g, 24 dm³ at 20 °C (293K) and one atmosphere pressure
• Percentage yield


  actual yield / theoretical yield x 100
• Atom economy


  mass of desired product / total mass of products x 100
• Homologous series


  Compounds which have the same general formula, similar chemical properties, show a gradation in physical properties and successive members differ by a CH2 unit
• Functional group


  Reactive group within a compound
• Structural isomers

  Molecules which have the same molecular formula but a different structural formula
• Geometric isomers


  Molecules with the same structural formula, but different arrangement of atoms due to the presence of one or more C=C bond
• Saturated hydrocarbon


  Contains no C=C bond
• Hydrocarbon


  Contains hydrogen and carbon only
• Substitution


  Replacing one atom or group with a different atom or group
• Homolytic fission


  Bond breaking in which one of the shared electrons goes to each atom
• Heterolytic fission


  Bond breaking in which both electrons in the shared pair go to a single atom
• Radical


  A particle with an unpaired electron
• Unsaturated hydrocarbon

  Contains at least one C=C
• Sigma bond


  A covalent bond formed by the linear overlap of atomic orbitals
• Pi bond


  A covalent bond formed by the sideways overlap of p orbitals
• Bond length


  The distance between the nuclei of two covalently bonded atoms
• Hydrogenation


  Addition of a hydrogen molecule across a C=C
• Electrophile


  An ion or molecule that attacks regions of high electron density
• Primary carbocation

  A carbocation which has one carbon atom directly bonded to the positively charged carbon
• Secondary carbocation


  A carbocation which has two carbon atoms directly bonded to the positively charged carbon
• Tertiary carbocation


  A carbocation which has three carbon atoms directly bonded to the positively charged carbon
• Polymerisation


  Joining together of many small molecules (monomers) to form a large molecule
• Monomers


  Many small molecules which join together to form a polymer
• Polymer


  A large molecule formed when monomers join together
• Primary halogenoalkane


  A halogenoalkane which has one carbon atom directly bonded to the carbon atom that is honded to the halogen. (Exceptions are halomethanes.)
• Secondary halogenoalkane


  A halogenoalkane which has two carbon atoms directly bonded to the carbon atom that is bonded to the halogen
• Tertiary halogenoalkane


  A halogenoalkane which has three carbon atoms directly bonded to the carbon atom that is bonded to the halogen
• Reflux


  Repeated boiling and condensing of a (reaction) mixture
• Hydrolysis


  Breaking up molecules by reaction with water
• Nucleophile


  An ion or molecule, with a lone pair of electrons, that attacks regions of low electron density
• Elimination


  A reaction in which a small molecule is removed from a larger molecule
• Miscibility


  Liquids which mix in all proportions i.e. form a single layer
• Primary alcohol


  An alcohol which has one carbon atom directly bonded to the carbon atom that is bonded to the -OH group. (Exception is methanol)
• Secondary alcohol


  An alcohol which has two carbon atoms directly bonded to the carbon atom that is bonded to the -OH group
• Tertiary alcohol


  An alcohol which has three carbons atoms directly bonded to the carbon atom that is bonded to the -OH group
• Ground state (infrared spectroscopy)


  A molecular vibration which is in the lowest possible energy state
• Wavenumber


  The reciprocal of the wavelength and it is measured in cm³