Topic 6

• What is empirical formula?

  The simplest whole number ratio of atoms of each element in a compound.
• What is molecular formula?

  The true number of atoms of each element in a compound.
• What is general formula?

  All members of a homologous organic series follow the general formula. For example, alkanes have the general formula CnH2n+2.
• What is structural formula?

  Shows the structural arrangement of atoms within a molecule. For example, CH3CH2COCH3.
• What is displayed formula?

  Shows every atom and every bond in an organic

  compound.
• What is skeletal formula?

  Shows only the bonds in a compound and any

  non-carbon atoms. The vertices are carbon

  atoms and hydrogen is assumed to be bonded to

  them unless stated otherwise.
• Naming compounds?

  1 Carbon atom: Meth-

  2 Carbon atoms: Eth-

  3 carbon atoms: Prop-

  4 carbon atoms: But-

  5 carbon atoms: Pent-

  6 Carbon atoms: Hex-

  7 Carbon atoms: Hept-

  8 carbon atoms: Oct-

  9 Carbon atoms: Non-

  10 Carbon atoms: Dec-
• How to name functional groups?

  Alkane: -ane

  Alkene: -ene

  Alcohol: -ol

  Carboxylic acid: -oic acid

  Ketone: -one

  Aldehyde: -al

  Ester: -ate

  Amine: -Amine
• If halogen is present?

  Fluorine: Fluoro-

  Chlorine: chloro-

  Bromine: Bromo-

  Iodine: Iodo-
• What are properties of homologous series?

  Same general formula

  same functional groups
• What are the three types of isomers?

  positional, functional and chain
• Explain why stereoisomerism can occur in alkenes?

  The c=c bond restricts rotation and cannot rotate. The groups cannot change positions.
• Describe a chemical set you wald carry out to distinguish between hexane and hex-1-ene?

  Bromine water test.
• what are two types of polymerisation?

  Addition polymerization and condensation polymerization.
• What is bond fission?

  is the breaking of the covalent bond. The electron pair in the bond can be distributed in two ways.
• What are the two types of bond fission?

  Homolytic and heterolytic.
• What are site of attack?


  electron deficient sites

  electron rich sites (lone pairs and double bonds)
• What are attacking species?

  • Free radicals (species with unpaired electron)
  • Electrophiles ( + charge accepts electrons attracted to electron rich centres)
  • Nucleophiles (- charge ) donates an electron pair to an electrophile to form a bond.
• What is a heterolytic?


  One Is more electronegative than the other.

  Cations= electron rich sites= Electrophilles

  Anion= electron deficit sites= Nucleophilles
• What is homolytic?

  Same electronegativity and is a free radical
• What are halogenation of the alkanes?

  • Alkanes are unreactive due to lack of polarity.
  • C and H have similar electronegativity.
  • In the presence of UV light or (300 degrees) the halogen will substitute a hydrogen in an alkane, a halogenalkane and hydrogen halide is produced.
• Reactions that occur in light are called photochemical reactions
• Alkane + Halogen—-> Hx + haloalkane
• What are the conditions of free radical substitution?

  Reactants: Alkane + Halogen

  Products: Haloalkane + Hydrogen halide

  Condition: Uv light

  Bond fission: Homolytic fission

  Attacking molecules: Free radicals
• Why is sigma bond stronger than pi bond?

  Sigma bonds have a direct overlap of the orbitals and gives it a greater area than the sideways overlap of pi bonds.
• A free radical has an unpaired electron.
• Alkene + halogen—> Dihaloalkane
• Alkene + H2–> Alkane
• Alkene + Hx—> Monosubstituted Haloalkane (STP)
• Alkene + steam—> Alcohol
• What is an addition reaction?

  A reaction where two molecules react together to produce one.
• What is the reaction of alkane and hydrogen?

  Addition or reduction
• what conditions are needed for the reaction of alkenes and hydrogen?

  Nickel Catalyst
• What conditions are needed for the reaction of alkenes and bromine or chlorine?

  Room temperature
• What is a chain isomerism?

  Same molecular formula but different arrangement of the carbon skeleton.
• What is positional isomerism?

  Same molecular formula but different position of the functional group on the carbon skeleton.
• What is functional group isomerism?

  Same molecular formula but different functional groups.
• What is stereoisomerism?

  are molecules with the same molecular formula and the same arrangement of covalent bonds but with different spatial orientation of the group.
• What is geometric isomerism?

  involves a c=c bond which has no free rotation.
• What is the rule for geometric isomers?

  • There must be a c=c bond
  • Each carbon in the atom must have 2 different groups attached to it.