L3 shape, groups +isomers

• carbon can form long chains because it can bond to 4 other atoms
• carbon is tetravalent
• when is carbon tetrahedral shaped

  when all carbon bonds are single
• carbon named based on how many carbons are in the longest carbon chain in the molecule
• hydroxyl

  OH-
• amino

  -NH2
• Sulphhydryl

  -SH
• carbonyl


  C=O
• carboxyl

  O=C-OH
• phosphate


  O=P -OH -OH -OR
• amines can except protons to become positively charged
• amines are fully protonated at pH 7
• Sulphhydryl's are thiols
• disulphide bridges through sulphhydryl functional groups
• how many R groups for aldehyde

  1
• how many R groups for ketone

  2
• amides have 1 R group and an amine group (NH2)
• carboxylic acids are fully dissociated at pH 7
• define isomers

  same number of atoms but different structure
• name the 3 types of isomerism

  structural, geometric, enantiomers
• structural isomers


  differ in covalent partners
• geometric isomers


  differ in arrangement around a double bond
• geometric isomers due to lack of rotation around a double bond
• cis isomers

  2 R groups are on the same side
• trans isomers

  the 2 R groups are on opposite sides
• enantiomers

  differ in spatial arrangement around a chiral carbon
• enantiomers are mirror images of one another meaning

  they cannot be superimposed upon one another
• enantiomers have identical

  physical and chemical properties
• enantiomers differ in how they interact with other optically active compounds
• the amino acid that contains a thiol group is

  cysteine
• chiral carbon defined by


  4 different groups around the carbon atom
• enantiomers rotate light plane polarised light in opposite directions