Structural formula of methnamin

The structural formula shows how the atoms are arranged and bonded together in a molecular formula of a chemical compound. Let's take a look at the compounds vinegar and ethyl alcohol, and compare their molecular formulas with their structural formulas:

 

Structural formulas of acetic acid and ethyl alcohol

 

Without the structural formula, we wouldn't know that acetic acid has a carbon atom double bonded together with oxygen. By looking at the structural formula, we can see the spatial arrangement of the atoms in the compound.

Structural Formula: Types and Examples

It is always good to have choices, and the same goes with how we draw structural formulas. There are different ways to represent a compound's structural formula. The earlier examples illustrate just one way of drawing the structural formula. In this upcoming section, we'll look at the different types of structural formulas.

The electron dot structural formula representation uses dots to represent the electrons involved with the bonding between different atoms. Let's take a look at the following compounds: water, ammonia and ethanol. Here, you can see the nonbonding electrons in red and the bonding electrons between the atoms in black:

 

Examples of the electron dot structural formula

 

Line-bond structural formula: The line-bond structural formula is a very commonly used representation of the structural formula. Like the name suggests, the line-bond structural formula uses lines and bonds to show the covalent bonds between atoms. This gives us a simpler and less cluttered representation of the structural formula. Instead of drawing dots between atoms, we draw lines. One line is equivalent to one pair of bonding electrons. The red dots are the nonbonding electrons. Here are the line-bond structural formula versions of the same compounds shown in the electron dot formula representation:

 

Examples of the line-bond structural formula

 

For organic compounds (carbon containing compounds) like ethanol, we usually don't show the nonbonding electrons, the red dots. We can omit the nonbonding electrons, the red dots, for organic compounds.

Condensed structural formula: The condensed structural formula still uses lines between bonded atoms, but is an easier and shorter way to draw the line-bond structural formula because it omits the carbon and hydrogen bonds. We can see this when we compare the line-bond structural formula with the condensed structural formula.