11.1 Carbon compounds

• Carbon can form rings and very long chain which may be branched because:

  • A carbon atom has 4 electrons in its outer shell so can form 4 covalent bonds
  • carbon-carbon bonds are relatively strong and non-polar
• The carbon-hydrogen bond is strong and relatively non-polar
• The molecular formula is the formula that shows the actual number of atoms of each element in the molecule
• The displayed formula shows every atom and every bond in the molecule
• • The structural formula shows the unique arrangement of atoms in a molecule in a simplified form, without showing all the bonds
  • Each carbon is written separately with the atoms or groups that are attached to it
  • Branches in the carbon chains are shown in brackets
• In skeletal formulae, straight lines represent carbon-carbon bonds
• As electrons are negatively charged, they tend to move from areas of high electron density to more positively charged areas
• A lone pair of electrons will be attracted to the positive end of a polar bond
• The movement of a pair of electrons is shown by a curly arrow that starts from a lone pair of electrons or from a covalent bond and moves towards a positively charged area of a molecule to form a new bond
• Free radicals occur when a covalent bond breaks resulting in one electron going to each atom that originally formed the bond and so these fragments of the original molecule have an unpaired electron - they are extremely reactive