basic concepts of hydrocarbons

• Alkanes

  CnH2n+2
• Alkenes

  CnH2n
• Alcohols

  CnH2n+1OH
• molecular formula

  actual number of atoms in molecule / element
• empirical formula

  the simplest whole number ratio of atoms in a compound
• structural formula

  arrangement of atoms in a molecule without showing all bonds
• skeletal formula

  show the bonds of carbon skeleton only hydrogen and carbon atoms not shown functional groups are
• displayed formula

  show arrangement of atoms showing all the bonds and atoms in the molecule
• Homologous series

  group of componds that have the same functional group and general formula

  use the general formula to work out molecular formula of a compound

  successive members of same homologous series increases be CH2
• alkanes suffix

  -ane
• alkanes branched

  alkyl
• Alcohols

  -ol
• aldehydes

  -al
• ketones

  -one
• carboxylic acid

  -oic acid
• halogen alkanes

  floro- bromo- iodo- chloro-
• cycloalkanes

  cyclo- -ane
• esters

  alkyl- -anoate
• carbon skeleton types -aromatic

  contain benzene ring

  may have functional groups coming from this
• carbon skeleton types-aliphatic

  straight branched or non aromatic chains
• alicylic compounds

  rings that are not aromatic
• alkyl groups

  hydrocarbons branches with a general formula CnH2n+1
• Nomenclature

  1) find length of stem by counting longest continuous chain of carbons

  2)functional group on the molecule normally tells you the ending of the name suffix

  3)number the carbon chain so the functional group sits on lowest possible number carbon

  4)make note of carbon number the ... is attached to, place before the suffix

  eg but 1 ol

  5) any side chains and less important functional groups written as prefixes in alphabetical order

  6) if there is more than 1 identical functional group or side chain put di(2) tri , tetra
• nomenclature numbers

  1- meth

  2- eth

  3- prop

  4- but

  5- pent

  6- hex

  7- hept

  8- oct

  9- non

  10- dec
• chemical mechanisms

  show movement of electrons during chemical reaction
• curly arrow

  show movement of pair of electrons

  always start from area with electrons eg double covalent bond \lone pair

  they end where you are moving electron to or the formation of a new bond

  free radical mechanisms dont require curly arrows
• bond fissions

  breaking of covalent bond

  electron pair wil be disturbed in 2 ways
• heterolytic fission

  bond breaks but the electrons are distributed unequally to form 2 different ions (cation and anion)

  double headed arrow shows the movement of pair of electrons

  
• Homolytic fission

  bond breaks with pair of electrons of electrons in the bond being shared equally to form 2 uncharged radicals the act means there are unpaired electrons on the atom

  
• Structural isomers

  have the same molecular formula but different structural formula
• Chain isomers

  same molecular formula but different arrangement of the carbon skeleton
• positional isomers

  same molecular formula different position of functional group on carbon skeleton
• functional group isomers

  same molecular formula but different functional group