You should already know! :
- What a hydrocarbon is?
- About single, double and triple bonds.
- About naming sub-groups.
If you don't any of this then please look up the As chemistry modules before continuing any further.
What is a benzene?
A benzene is a hydrocarbon with 6 carbons and 6 hydrogens. Now at first glance this seems inpossible since carbon must form 4 bonds. However Friedrich August (great month) von Kekule's theory is that it was a ring of carbon atoms with alternate single/double bonds. Now this something that we as chemists accept and are taught. However I hate to break this to you but this is actually wrong! Well not wrong, wrong but there is evidence why it isn't actually the case.
Right confused? Ok the single/double bonded ring works because all the hydrogens bond to one carbon, yet the carbon is capable of making the 4 bonds. However if you remember alkenes then you'll remember that they like to react and make all sorts of magical things, benzene however can only burn (making a very smoky flame) and partake in electrophilic substitution, this means that is contradicts the whole presence of a double…