MOD 7: ORGANIC CHEM

• Carbon


  In organic compounds, carbons always form four bonds
• Single bonds


  • C - C
• Double bonds


  • C = C
• Triple bonds


  • C ≡ C
• Carbon will also bond with hydrogen, oxygen, nitrogen and sulfur
• Alkanes


  A homologous series → group of compounds that have similar chemical structures and properties and the same general formula
• Alkanes


  • Only contain single bonds (C-C) → suffix 'ane'
  • Are saturated hydrocarbons → their carbon backbones contain NO double or triple bonds
• Types of alkanes


  • Straight chained: carbon atoms are connected in one continuous chain with no branches → are saturated
  • Branched: contain only C and H (only C - C single bonds) and are not linear
  • Cyclic (cyclo): are arranged in a ring structure
• Carbons with at least one double or triple bond are called unsaturated hydrocarbons
• Drawing alkanes


  1. Use the main name to draw the main chain

  2. Identify the branches

  3. Add the branches to the main chain

  4. Add hydrogen atoms to complete the structure → each carbon should have four bonds
• Alkenes


  • Are a homologus series
  • One pair of carbons is joined by a double bond → rest are joined by single bonds
  • Are unsaturated compounds
  • Alkenes end in "ene"
• Naming alkenes


  1. Check the bonding of the carbon backbone/parent chain (i.e. double bonds)

  2. Determine the longest continuous chain containing the double bond

  3. Determine the location of the double bond by numbering the carbon atoms from the end of the chain closest to the double bond

  4. Name the branches

  5. Branches are formed similarly to alkanes BUT the lowest number is assigned to the double bond and not the branch

  6. List the names of the branches in alphabetical order
• Alkynes


  • Are a homologus series
  • One pair of carbons joined by a triple bond (C ≡ C)
  • Are unsaturated compounds
  • All alkynes end in "yne"
• Halogenated organic compounds


  • Are group 7 elements (Br, Cl, F and I)
  • Simplest class is haloalkanes
  • Any organic compound that contains one or more hydrogen atoms:
• Halogens


  • Bromine → -bromo
  • Chlorine → -chloro
  • Fluorine → -fluoro
  • Iodine → -iodo
• Naming halogenated organic compounds


  1. Name the main chain, including the position of double or triple bond

  2. If no double/triple bonds, the numbering starts from the C with the halogen

  3. Alkyl side chains are identified and numbered as normal

  4. Halogen atoms are identified and numbered like any alkyl group

  5. Halogen branches are put into alphabetical order
• • When allocating numbers to halogens, the overall combination of numbers must be as low as possible
  • If two options are the same, the element that comes first alphabetically must have the lowest set of numbers
• Isomers


  Two or more compounds with the same formula but different arrangements of atoms and physical properties
• Types of isomers


  • Chain isomers: Exist due to the possibility of branching
  • Position isomers: Exist for hydrocarbons that contain functional groups
  • Functional group isomers: Share the same molecular formula but will have different functional groups
• Locant


  A figure to indicate the position of a functional group with a molecule
• Propanal


  • Aldehydes (a class of organic compounds that contain another functional group)
  • C=O bond located at the end of the carbon chain
  • Comes from tobacco
• Propanone


  • Ketones (don't have any H atoms attached to the carbon that has a double bonded oxygen)
  • C=O bond located in the middle/centre of the carbon chain
  • Powerful, organic solvent
  • Commonly known as acetone
• Melting and boiling points of alkanes


  Increase with increasing molecular weight due to stronger intermolecular forces
• As molecular weight of alkane increases

  • Size and surface area of molecule increase
  • Larger electron cloud forms
  • Allows temporary dipole-dipole and induced dipole-dipole forces
  • Leads to stronger dispersion forces
• Stronger intermolecular attractions


  More energy needed to overcome, leading to higher melting and boiling points
• VESPR theory


  Valence shell electron pair repulsion theory
• VESPR theory


  • Negative charge on electron clouds
  • Bonds repel each other rather than attract
  • When four single bonds form around carbon, electrons repel
  • Bonds rearrange symmetrically around central carbon
  • Singly bonded compounds have tetrahedral shape
  • Each bond equally spread apart from nearest neighbouring bond
• Tetrahedral molecules


  Form four single bonds with other atoms
• Tetrahedral molecule


  • Carbon tetrachloride
• Diamond


  • Hardest natural substance
  • Infinite lattice arrangement of singly bonded carbon atoms
  • Emphasises stability and geometrical symmetry of four single carbon atoms
• Tetrahedral and straight chain molecules

  • Tetrahedral formation of four single bonds around carbon gives straight chained carbon molecules a zig-zag shape
• Alkane properties


  • Name
  • Molecular formula
  • Molecular weight
  • Melting point °C
  • Boiling point °C
• Methane: CH4, 16, -182, -164
• Ethane: C2H6, 30.1, -183, -88
• Propane: C3H8, 44.1, -190, -42
• Butane: C4H10, 58.1, -138, 0
• Pentane: C5H12, 70.15, -129.8, 36
• Hexane: C6H14, 86.2, -95, 69
• Heptane: C7H16, 100.2, -90, 98
• Octane: C8H18, 114.2, -57, 126