Aromatic chemistry

content Structures of molecules Bonds of atoms When is it aromatic? Kekule Why is the structure not right?

Structures of molecules Carbon has four bonds and can connect with other atoms The molecule can have a number of carbon atoms (C), depending on how many c's, there are prefixes. For example: 1C= meth 3C= prop 5C= pent 2C= eth 4C= but 6C= hex 7C= hept 8C= oct

Bonds of atoms All atoms have a different number of bonds, for example: hydrogene (H)= 1 carbon (C)= 4 oxygen (O)= 2 nitrogen (N)= 3 There can be a single bond or a double bond, also there can be a triple bond, it depends on the number of the bonds the atom has.

What prefix is this? A= pent B= hex C= but

How many bonds does nitrogen have? (answer from the other question: c) A: 2 B: 3 C: 4

When is it aromatic? Every line= 2 electrons -you have to use the formula 4n+2 The one in the picture has 8 electrons 4n+2=8 N= 1,5 it is not aromatic because it is not a round number, otherwise it would be aromatic

Kekule Kekule thought that there was a ring structure for benzene, with single and double bonds. Each of the carbon atoms has single as well as a double bond to the two neighbouring carbon atoms.

Why could Kekule's structure not be right? In the structure by Kekule, the bonds have got different lengths (double bonds are shorter) In reality, all bonds have the same length, in between a single and a double bond. Benzene is very stable, comparing to other atoms with more double bonds.