Explanation:
With the help of models we get to know how atoms are bonded with each other. As a model tells how many numbers of atoms are attached to a central atom. Therefore, a models tells us the shape of a molecule.
For example, structure of [tex]CO_{2}[/tex] molecule is as follows.
O = C = O
Hence, structure of [tex]CO_{2}[/tex] is linear in shape.