Chemistry

• Condensed structures


  Repeating units are collected together and the bonds are omitted
• Bond-line representations

  • Quick and easy to write (with practice)
  • The most expressive and concise approach
  • The standard for modern organic chemistry
  • Draws attention to the relevant (reactive) parts of the molecule and plays down the less relevant (unreactive) parts (e.g. hydrocarbon chains)
  • Give a much greater emphasis to the overall shape of the molecule and demand a consideration of true bond angles
  • Each C-C bond is represented as simply - and all the hydrogen atoms are omitted
  • Each apex or line–end represents a carbon atom unless another symbol is specified
  • All the valence bonds omitted from carbon are to hydrogen atoms by default

  
• Carbon valency


  Carbon has a valency of 4, which means it can form 4 bonds
• Carbon chain prefixes


  • Meth
  • Eth
  • Prop
  • But
  • Pent
  • Hex
  • Hept
  • Oct
  • Non
  • Dec

  
• Branched compounds


  The name is dictated by the longest chain in that molecule
• Functional groups


  • Alcohol
  • Acyl chloride
  • Aldehyde
  • Alkane
  • Alkene
  • Alkyl halide
  • Alkyne
  • Amide
  • Amine
  • Carboxylic acid
  • Ether
  • Ester
  • Ketone
  • Nitriles (or cyanides)
  • Nitro

  
• Aromatic compounds


  • Benzene
  • Pyridine
  • Phenol
  • Aniline

  
• Organic synthesis


  The construction of organic molecules (which mainly contain C, O, N and H), into other organic molecules, via organic reactions
• Synthesis of paracetamol


  Starting material is phenol, transformed into paracetamol via three steps or reactions
• Periodic table trends


  • Ionization energy
  • Electron affinity
  • Electronegativity

  
• Ionic bond


  Formal transfer of electron(s), electronegativity difference > 1.7
• Covalent bond


  Sharing of electrons, electronegativity difference < 1.7
• Polar covalent bond


  Electronegativity difference between 0.4 and 1.7, electrons unequally shared
• Non-polar covalent bond


  Electronegativity difference equal to or less than 0.4, electrons equally shared
• Covalent bond

  Sharing of electrons
• Polar covalent bond


  Electrons are unequally shared between the atoms because the atoms on the bond have a significant difference in electronegativity
• Polar covalent bonds


  • Formed when the electronegativity difference between the atoms is between 0.4 and around 1.7
  • Non-polar covalent bonding is when electronegativity difference between the atoms is equal to or less than 0.4
• Polar bonds are represented by δ+ and δ- or an arrow
• Polarity


  Due to the polar nature of the water molecule itself, polar molecules are generally able to dissolve in water
• Hydrophilic


  Water loving
• Hydrophobic


  Water hating
• Dative covalent bond


  An atom donates two electrons to form a new bond
• Van der Waals forces

  Weak interactions between molecules caused by temporary imbalances of charge distribution
• Dipole-dipole interactions


  Result when two polar molecules approach each other in space, the partially negative portion of one is attracted to the partially positive portion of the other
• Hydrogen bond

  Weak bond (1/10 strength of covalent) formed between electron rich atoms (like N, O and F) and hydrogen atoms in polar covalent bonds
• Intramolecular bonds

  Existing or taking place within a molecule
• Intermolecular bonds

  Existing or taking place between molecules
• Molecules/atoms react because they can move and collide with sufficient energy and favourable alignment of electronic orbitals
• Electrophile

  Molecule/atom which accepts electrons to form a new bond
• Nucleophile

  Molecule/atom which donates electrons
• Organic reaction mechanisms show the movement of electrons in a chemical reaction to depict the bond making and breaking processes
• Equilibrium

  When a system at equilibrium is disturbed, the equilibrium readjusts itself to counteract the effect of the applied change and will work to establish a new equilibrium
• Amines reacting with halogens

  1. Primary amine

  2. Secondary amine

  3. Tertiary amine

  4. Quaternary amine

  
• Electrophilic aromatic substitution


  1. Halogenation

  2. Nitration

  3. Sulfonylation

  4. Alkylation

  5. Acylation
• Molecules have a 3D structure defined by the bonding present, which is dictated by the shape of the orbitals
• Orbital


  A region or volume where an electron is most likely to be found

  
• Orbital hybridisation


  Atoms 'mix' their atomic orbitals to optimise the geometry and minimise the energy of the molecules they are included in

  
• sp3 hybridisation

  The s orbital combines with 3 p orbitals to give 4 equivalent sp3 hybrid orbitals in a tetrahedral arrangement

  
• sp2 hybridisation

  Two p orbitals combine with the s orbital to give three sp2 orbitals in a flat triangular arrangement with a perpendicular p orbital

  
• sp3 orbitals


  Four hybrid orbitals that combine to give a tetrahedral shape