Organic Chemistry + Alkanes/Alkenes

Carbon based, except for CO2 (inorganic)
Carbon can produce such a diverse range due to 4 outer electrons so 4 covalent bonds
1. non- polar and stable
Classifications
1. Homologous series = related compounds with similar structure and generalised formula
  1. so similar chemical properties
2. Hydrocarbons = molecules made up of only carbon and hydrogen
  1. Alkynes = triple C-C bonds
3. Aliphatic = Carbon atoms joined in straight unbranched chains
  1. Alicyclic = Carbon atoms joined in rings
    1. prefix - cyclo
4. Aromatic = contains a benzene ring
  1. unreactive as each carbon has only 1 electron not used for bonding
5. Functional group = group of atoms added onto a carbon chain responsible for reactivity
Naming
1. 1) Identify longest continuous carbon chain
2. 2) Identify any side chains ( meth, eth, prop show how long and 'thyl' shows its a side chain)
3. 3) Use numbers to show where on the parent chain, the side chains are positioned
  1. Number as low as possible
4. If 2 possible parent chains, choose the one with most branches
5. Halogenalkanes prefix-
  1. Fluoro
  2. Chloro
  3. Bromo
  4. Iodo
6. Alcohols suffix - ol
7. Aldehydes suffix -al
8. Ketones suffix -one
9. Carboxylic acids suffix - oic acid
10. Ester suffix - oate
Representing Formula
1. Molecular formula = shows number and type of atom, but not how they're joined
2. Empirical Formula = shows the simplest whole number ratio of atoms
3. General Formula = simplest formula for all members of a homologous series
4. Displayed Formula = shows all the bonds in a structure
5. Structural Formula = shows how atoms/ groups are arranged but NOT all the bonds e.g CH3(CH3)
6. Skeletal Formula = simplified carbon backbone
7. Isomerism
  1. Structural Isomerism = same molecular formula but a different structural formula
    1. Positional Isomers = same functional group can be at different positions along the carbon chain
    2. Functional Isomers = different functional groups yet the same molecular formula
Reaction Mechanisms
1. Curly arrows represent the movement of electrons
  1. single headed arrow represents the movement of a single electron
2. Homolytic bond fission
  1. Bond breaks into 2 equal parts, each atom takes 1 electron from the shared bonds forming radicals
  2. Radical = species with a single unpaired electron
    1. Very reactive
  3. Often photo-chemical / gaseous processes
  4. this occurs with halogens with high UV energy
3. Heterolytic bond fission
  1. Bond breaks unevenly, one atom takes both electrons forming ions
  2. Often aqueous / polar bonds
4. show the steps of a reaction in electron and molecule transfer
5. Radical Substitiution
  1. 1) Initiation Step (forms radical)
  2. 2) Propogation (radical makes a new radical)
  3. 3) Chain reaction - unpredictable
  4. Termination (radical meets another radical and s reaction stops)
  5. Alkanes react with Halogens to produce Haloalkanes via Radical Substitution
  6. end up with a mixture of products
6. Types of Reaction
  1. Substitution (molecule is replaced for a more reactive one)
  2. Elimination (small molecule removed from a larger one)
  3. Addition (2 molecules reacting to form a 1 molecule)
Alkanes
1. CnH2n+2
2. Saturated
3. Hydrocarbons
4. Tetrahedral, 109.5
5. non-polar
6. Don't dissolve in water
7. bpt increases as chain increases
  1. due to more points of contact so stronger IMF
8. C1-C4 are gaseous and fuels combust to produce lots of energy as exothermic
9. C5-C16 are colourless liquids
10. C17+ white waxy solids
11. sigma bonds = result from the direct overlap of 2 atomic
Alkenes
1. unsaturated
2. Hydrocarbons
3. CnH2n
4. Trigonal Planar 120
5. pi bonds = result from sideways overlap of p orbitals
  1. pi bonds are weaker than sigma bonds
  2. only occur in alkenes
  3. alkenes are more reactive as pi bonds break and electrons can form new bonds
6. Stereoisomerism
  1. same molecular and structural formula yet a different arrangement in space
  2. Double bond means there is no free rotation
  3. Cis / trans if one of the attached groups are Hydrogen
  4. E/Z if the attached groups aren't hydrogen
  5. Higher atomic number = higher priority
  6. opposite sides = E
  7. same side = Z
7. Reactions
  1. Electrophile = Atom/ group of atoms attracted to an electron rich area accepting an electron pair to form a new bond
  2. Electrophillic Addition
  3. induced dipole causes heterolytic bond fission of Br2
    1. causes a carbo - cation to be formed
  4. needs UV light to occur to break halogen bond
  5. Test for an alkene = turns bromine water colourless
  6. Markownikoff's rule
    1. 2 step process with carbocation intermediate, the prefered route depends on stability
    2. Most stable is a tertiary chain
  7. Hydrogenation
    1. When adding H2
    2. Nickel Catalyst, 150 dC
    3. causes an alkane to form, pack together better and more solid
  8. With H20
    1. produces a saturated alcohol
    2. Phosphoric acid catalyst
    3. high pressure
    4. gaseous atoms, higher than 100 dC

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Organic Chemistry + Alkanes/Alkenes

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