Page "Chemical bond" Paragraph 27

The fact that atoms and molecules are three-dimensional makes it difficult to use a single technique for indicating orbitals and bonds.

In molecular formulas the chemical bonds ( binding orbitals ) between atoms are indicated by various methods according to the type of discussion.

Sometimes, they are completely neglected.

For example, in organic chemistry chemists are sometimes concerned only with the functional groups of the molecule.

Thus, the molecular formula of ethanol may be written in a paper in conformational, three-dimensional, full two-dimensional ( indicating every bond with no three-dimensional directions ), compressed two-dimensional ( CH < sub > 3 </ sub >– CH < sub > 2 </ sub >– OH ), separating the functional group from another part of the molecule ( C < sub > 2 </ sub > H < sub > 5 </ sub > OH ), or by its atomic constituents ( C < sub > 2 </ sub > H < sub > 6 </ sub > O ), according to what is discussed.

Sometimes, even the non-bonding valence shell electrons ( with the two-dimensional approximate directions ) are marked, i. e. for elemental carbon < sub >.</ sub >< sup >'</ sup > C < sup >'</ sup >.

Some chemists may also mark the respective orbitals, i. e. the hypothetical ethene < sup >− 4 </ sup > anion (< sub >