module 4 organic

• hydrocarbons = compound containing carbon and hydrogen only, and they are non polar molecules
• saturated hydrocarbon has single bonds only, e.g methane
• unsaturated hydrocarbon has carbon-carbon double bonds e.g propene
• homologous series is a family of compounds with similar chemical properties whose successive members differ by the addition of a -CH2 group
• functional group is the part of the organic molecule that is largely responsible for the molecule's chemical properties
• alcohol has an -OH functional group
• amines have a -NH2 functional group
• aliphatic hydrocarbons = carbon atoms are joined to each other in unbranched (straight) or branched chains or non aromatic rings

  
• alicyclic hydrocarbons = carbon atoms are joined to each other in ring (cyclic) structures, with or without branches

  
• aromatic hydrocarbons = some or all of the carbon atoms are found in a benzene ring

  
• alkanes = containing single carbon-carbon bonds

  general formula = CnH2n+2
• alkenes = contain at least one double carbon-carbon bond

  general formula = CnH2n
• alkynes = contain at least one triple carbon-carbon bond
• alkyl groups:

  1. methyl = CH3
  2. ethyl = C2H5
  3. propyl = C3H7
  4. butyl = C4H9
  5. pentyl = C5H11
• molecular formula = shows the number and type of atoms of each element present in a molecule

  e.g ethanol is C2H6O
• empirical formula = simplest whole number ration of the atoms present of each element present in a compound

  e.g glucose has a molecular formula of C6H12O6 so its now CH2O
• general formula is the simplest algebraic formula for any member of a homologous series

  e.g alkanes is CnH2n+2, carboxylic acids is CnH2nO2
• displayed formula = relative positioning of all the atoms in a molecule and the bonds between them

  
• structural formula = uses the smallest amount of detail possible to show the arrangement of the atoms in a molecule using groups of bonds

  e.g butane is CH3CH2CH2CH3
• skeletal formula = one line represents a singular bond and and intersection is one carbon bond

  
• structural isomers are compounds with the same molecular formula but different structural formula

  
• homolytic fission = the breaking of a covalent bond with one of the bonded electrons going to each atom, forming 2 radicals
• radical = an atom or groups of atoms with an unpaired electron
• homolytic fission of the carbon-carbon bond in ethane:

  H3C-CH3 -> H3C. + .CH3
• heterolytic fission = the breaking of a covalent bond forming a cation (positive ion) and an anion (negative ion)
• heterolytic fission of carbon-chlorine bond in chloromethane:

  H3C-Cl -> H3C+ + Cl-
• addition = two reactants form together to form a product

  
• substitution = an atom or group of atoms is replaced by a different atom or group of atoms

  
• elimination involves the removal of a small molecule from a larger one

  
• alkanes are saturated hydrocarbons containing only carbon-carbon single bonds joined together by covalent bonds
• each carbon atom is joined to 4 other atoms by covalent bonds = SIGMA BOND
• a sigma bond is a result of an overlap of 2 orbitals, one from each bonding atom
• each overlapping orbital contains one electron so the sigma bond has 2 unpaired electrons, and each carbon in an alkane has 4 sigma bonds
• carbon forms a tetrahedral shape with an angle of 109.5
• crude oil contains hundreds of different alkanes and oil refineries separate the crude oil into fractions by fractional distillation in a distillation tower
• separation of fractions is possible because the boiling points of the alkanes are different
• boiling point increases as chain length increases because the surface contact area increases so there are more londons forces and intermolecular forces between the molecules
• more branching decreases the surface area of contact on the chain so there are fewer londons forces and boiling point decreases
• C-C and C-H sigma bonds are strong
• C-C bonds are non polar