Constitutional Isomers

Because it is relatively clear that carbon has specific bonding patterns and that other atoms have specific bonding patterns, you can condense the way that organic molecules are written. They can be written in a condensed form, such as CH3CH2CH2OH, as well as in simple line form, in which there is no “C” written for carbon and no “H” written for hydrogen. These are called “line structures” as they look like zig-zagged lines. Only the hydrogens attached to molecules other than carbon are listed and all other atoms are listed in other than line form. Ring structures also do not have a special listing of the atoms separately but is shown as in figure 11:

Figure 11.

These line and ring structures are pared down in a way that it makes it easier to see the bonding and the way the structures are laid out. It tends to work best for larger and more cumbersome molecules; in the case of smaller structures, it is best to write them out without doing a line structure.

CONSTITUTIONAL ISOMERS

Constitutional isomers are the same as “structural isomers”. These are molecules that can be written the same way when writing the different carbon, hydrogen, and oxygen molecules but that look quite different. A typical example is fructose and glucose, which are sugar molecules. Both can be written as C4H12O6. How do you write this? Because these are two different molecules, you can imagine that they are different molecules. Figure 12 shows what these two molecules look like when drawn out: