Do bond classifications help or hinder chemistry?

There is something strange about the chemical bond. It is very difficult to define in a more sophisticated way than as being the ‘glue’ that ‘binds’ atoms. And yet the bond is one of the most essential concepts in chemistry; without it one cannot describe how molecules are structured, nor explain how a chemical reaction occurs.

Or so you’d think! Ambiguities around the nature of the chemical bond and borderline cases that fail to clearly fall under a particular type of bonding may be evidence that bonding and its types are merely conceptual constructs.

Chemists have developed an extensive classification system for bonds which includes not only the classic duo of ionic and covalent bonds, but also metallic, hydrogen, multi-centre bonds and more. While the classificatory scheme has proved extremely successful, a careful look at the definitions that characterise each type of bond shows that the nature of bonding is identified with strikingly different things. For example, in the context of the ionic bond it refers to ‘electrostatic attraction’, in that of covalent bonds it refers to ‘a region of high electron density’, and in that of hydrogen bonds it refers to ‘a form of association’.