Molecular Basics

The first two links show different ways of representing a molecular structure, using heptane as an example.

Accepted Ways of Depicting Heptane
There are many ways to draw the strucure of a given molecule. Although the structures may look different, all of them show the seven carbons and sixteen hydrogens of heptane bonded together in the same connective sequence.

Molecular Graphics of Heptane
These pictures try to show the actual shape of a molecule and the space that it occupies. Heptane is a flexible molecule and can assume different shapes or conformations. Two different conformations are shown here. With the aid of computers it is easy to generate such pictures of much larger molecules and predict their shapes and sizes.

This link compares heptane and its isomers.

Heptane and its Isomers
The heptane molecule is made up of seven carbon atoms and sixteen hydrogen atoms bonded together in a certain way. If these same atoms are bonded in a different connective sequence, we have what is called a structural isomer of heptane. Each isomer is a different chemical substance with different properties and a name of its own.