ASSESSMENT 3

• Nomenclature of organic chemicals, up to C8

  • Methane (CH4)
  • Ethane (C2H6)
  • Propane (C3H8)
  • Butane (C4H10)
  • Pentane (C5H12)
  • Hexane (C6H14)
  • Heptane (C7H16)
  • Octane (C8H18)
• Isomers


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


  • C4H10 (butane)
• Chain isomers


  • Exist due to the possibility of branching
  • Same molecular formula → Different molecular structure
• Position isomers


  • For hydrocarbons that contain functional groups
  • Same molecular formula and chain structure but a different position
  • Locant - a figure to indicate the position of a functional group with a molecule
• Position isomers


  • 1-butanol
  • 2-butanol
• Functional group isomers


  • Share the same molecular formula but will have different functional groups
  • May have different chemical and physical properties
• Functional group isomers


  • Propanal
  • Propanone
• 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
• Properties and trends within and between homologous series

  • Physical
  • Chemical
  • Boiling/melting point
  • Intermolecular forces
  • Density
  • Solubility
  • Reactivity
• Trends - chemical


  • Intermolecular
  • Intramolecular
  • Dispersion forces
  • Covalent bonding
  • Dipole-dipole forces
  • O-H bond strength
  • Hydrogen bonding
• Carbon


  • In organic compounds, carbons always from four bonds
  • Single bonds → C - C
  • Double bonds → C = C
  • Triple bonds → C ≡ C
  • Carbon will also bond with hydrogen, oxygen, nitrogen and sulfur
• VESPR theory


  • Valence shell electron pair repulsion theory
  • Negative charge on electron clouds
  • Bonds repel each other rather than attract
  • When four single bonds form around a carbon atom, the electrons repel
  • Bonds rearrange themselves symmetrically around the central carbon atom
• Single bonded compounds


  • Have a tetrahedral shape
  • Each bond is equally spread apart from the nearest neighbouring bond
• Tetrahedral molecules

  • Carbon tetrachloride
• Diamond


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

  • The tetrahedral formation of four single bonds around caron gives 'straight chained' carbon molecules a zig-zag shape
• Addition reactions


  A reaction in which atoms are added to a molecule by breaking a double or triple bond
• Combustion reactions


  • Alkanes and alkenes undergo combustion
  • Energy is often harnessed to power internal combustion engines, industrial furnaces etc
  • Complete combustion of hydrocarbons produce carbon dioxide
• Hydrogenation


  • Addition of hydrogen to a molecule
  • Alkenes are converted to alkanes
  • Addition of hydrogen to an alkene occurs in the presence of a metal catalyst (e.g. nickel)
• Hydration


  A dilute acid catalyst is required
• Halogenation


  • Addition of halogens to a molecule
  • Due to the reactivity of the halogens, a catalyst is not needed
• Addition of a hydrogen halide

  • Hydrogen halides - molecules with a hydrogen atom and a halogen atom
  • Hydrogen chloride and hydrogen bromide are common hydrogen halides
• Combustion of alkanes


  • Incomplete combustion - performed with limited oxygen, producing carbon monoxide and carbon
  • Releases less energy per mole of organic compound than complete combustion
  • Can occur for alkanes, alkenes, alkynes, alcohols, and other organic compounds
  • Fuel combustion is less efficient
  • Enthalpy of combustion decreases as the levels of oxygen available decreases
• Substitution


  Replacement of an atom on a molecule
• Substitution with halogens


  • Only occur with chlorine and bromine
  • Can also occur if the mixture is subjected to UV light
  • Substitution reactions continue until all the hydrogen atoms in the compound have been replaced by the halogen atoms
  • Occurs with only one halogen atom being substituted at a time
• Reactions of alcohols


  • Combustion
  • Dehydration
  • Substitution
  • Oxidation
• Combustion reactions of alcohols

  Alcohol + Oxygen gas