Homologous Series

Homologous Series

1. Organic Chemistry

   • most fuels based around a chain of carbon atoms
     • Carbons will be bonded to more carbons or hydrogens unless stated otherwise
       • could also have:
         • Oxygen
         • Nitrogen
         • Chlorine
         • Bromine
         • Iodine
   • Carbon atoms form 4 covalent bonds
     • could be made up of:
       • 4 single bonds
       • 1 double and 2 singles
       • 1 triple, 1 single

2. Representing Organic molecules

   • Molecular Formula
     • Gives basic information
     • number of atoms of each element present in 1 molecule
     • no indication of how atoms are bonded
       • often several molecules with same formula & different structures
   • Structural Formula
     • Drawings of the molecule
     • 3 types
       • Full
         • Shows every atom & bond
         • single bond : - double bond : =
       • Skeletal
         • quicker
         • bonds zigzagged
         • any bonds apart from C and H shown
       • Shortened
         • writes each carbon
           • groups attached to the right

3. Found in Fuels

   • Alkanes
     • simplest organic molecules
     • only carbon & hydrogen atoms
       • all bonds single
       • molecular formula CnHn+2
       • Can have branched chains
   • Cycloalkanes
     • only carbon and hydrogen
       • all bonds single
       • "ring" structure of carbons
   • Alkenes
     • have 1 or more double bonds
       • c=c known as functional group
         • give characteristic chemical properties different to alkanes
   • Arenes
     • ring of C atoms
       • between each pair of electrons, 6 delocalised
         • represented by circle inside carbon ring
     • Benzene- C6H6
   • Alcohols
     • one or more OH functional groups
       • sometimes referred to as hydroxyl groups
       • can be attached to any carbon along chain
         • full structural formula has to show single bond between O & H
   • Ethers
     • contain oxygen atoms
       • bonded between carbon atoms in chain
         • gives different chemical & physical properties to alcohols

4. group of chemicals

   • Similar structure
   • Similar molecular formula
   • Similar chemical properties
   • differ by number of carbons

5. systematic nomenclature

   • alkanes
     • "ane"
     • Rules
       • 1- find longest continuous C chain
         • single bonds can rotate
       • 2- name any branches (alkyl groups)
         • only C atoms not in chain counted
       • 3- number carbon atoms
       • 4- more than one on a branch gets name
       • 5- names of branches arranged alphabetically
   • alcohols
     • Rules
       • 1- longest continuous C chain
       • 2- remove 'e' replace with 'ol'
       • 3- insert number between 'an' and 'ol'
       • 4- any branches added named & numbered