Organic chemistry BI

• Organic chemistry


  Focuses on organic compounds, compounds that contain carbon atoms
• Elements and their preferred number of bonds

  • Hydrogen: 1 bond
  • Beryllium: 2 bonds
  • Boron: 3 bonds
  • Carbon: 4 bonds
  • Nitrogen: 3 bonds
  • Oxygen: 2 bonds
  • Fluorine, other halogens: 1 bond
• Drawing Lewis structures


  1. Determine preferred number of bonds for elements

  2. Arrange atoms to satisfy preferred number of bonds

  3. Add lone pairs to achieve stable octet
• Hydrogen bond


  Special type of covalent bond where hydrogen is directly attached to nitrogen, oxygen or fluorine
• Hydrogen bonding explains why water has a high boiling point
• Polar bond


  Bond where there is a difference in electronegativity between the two atoms of 0.5 or more
• Carbon-fluorine bond in methyl fluoride is a polar bond
• Carbon-hydrogen bond is a non-polar bond
• Covalent bond


  Electrons are shared between atoms, can be shared equally (non-polar) or unequally (polar)
• Ionic bond


  Electrons are transferred from one atom to another, not shared
• Common names of alkanes

  • Methane
  • Ethane
  • Propane
  • Butane
  • Pentane
  • Hexane
  • Heptane
  • Octane
  • Nonane
  • Decane
• Condensed structure


  Shorthand way to represent organic molecules, shows number of hydrogen atoms on each carbon
• Alkene


  Organic compound with at least one carbon-carbon double bond
• Alkyne


  Organic compound with at least one carbon-carbon triple bond
• Bond lengths

  • Single bond > double bond > triple bond
  • Single bond: 154 pm
  • Double bond: 133 pm
  • Triple bond: 120 pm
• Bond strengths

  • Triple bond > single bond
  • Sigma bond > pi bond
• Bond order

  Single bond: 1<|>Double bond: 2<|>Triple bond: 3
• Hybridization

  Determined by number of atoms/groups attached to carbon and number of lone pairs<|>sp3: 4 groups<|>sp2: 3 groups<|>sp: 2 groups
• CH bond in methane is sp3-s hybridized
• CH bond in alkyne is sp-s hybridized
• This molecule has 6 sigma bonds and 2 pi bonds
• Hybridization


  The type of bonding an atom has
• Determining hybridization of C-H bond

  1. Identify carbon atom

  2. Determine number of atoms attached to carbon

  3. Assign hybridization based on number of bonds
• Hydrogen is always s hybridized
• Bonds in organic compound

  • Sigma bonds
  • Pi bonds
• Calculating number of sigma and pi bonds

  1. Count all sigma bonds

  2. Identify double/triple bonds and count pi bonds
• Formal charge


  The charge on an atom in a molecule, calculated as: valence electrons - bonds - lone pairs
• Formal charge calculations

  • Carbon with 4 bonds, 0 charge
  • Carbon with 3 bonds and 1 lone pair, -1 charge
  • Carbon with 3 bonds, +1 charge
• Bonding electrons

  Electrons shared between atoms in a bond
• Nonbonding electrons

  Electrons not shared between atoms, in lone pairs
• Alcohol


  Functional group with C-O-H
• Aldehyde


  Functional group with C=O and H
• Ether


  Functional group with O between two C atoms
• Ketone

  Functional group with C=O in the middle of the chain
• Ester


  Functional group with C=O and O-C
• Carboxylic acid


  Functional group with C=O and O-H
• Expanding condensed structures

  1. Identify C, H, and other atoms

  2. Draw out full Lewis structures
• Methyl groups are at the end of structures
• CH2 groups are in the middle of structures
• CH groups tend to branch off and have other atoms attached