What is a structural formula? What is the difference between a structural formula and a molecular model?
The structural formula of a chemical compound is a graphic representation of the molecular structure, showing how the atoms are arranged. The chemical bonding within the molecule is also shown, either explicitly or implicitly. Unlike chemical formulas, which have a limited number of symbols and are capable of only limited descriptive power, structural formulas provide a complete geometric representation of the molecular structure.
For example, many chemical compounds exist in different isomeric forms, which have different enantiomeric structures but the same chemical formula.
A structural formula is able to indicate arrangements of atoms in three dimensional space in a way that a chemical formula may not be able to do.
Before moving forward first we have to know the molecular model
A molecular model , is a physical model that represents molecules and their processes. The creation of mathematical models of molecular properties and behaviour is molecular modelling, and their graphical depiction is molecular graphics, but these topics are closely linked and each uses techniques from the others. "molecular model" will primarily refer to systems containing more than one atom and where nuclear structure is neglected. The electronic structure is often also omitted or represented in a highly simplified way.