In essence, organic chemistry is all about the interaction between electron-rich atoms or molecules and electron-deficient atoms or molecules. The concept of nucleophiles and electrophiles dates back to 1933, 2 when it was introduced by Ingold based on Lewis's electronic theory of valency and the acid-base theory of Brøndsted and Lowry. Over the years, nucleophilicity and electrophilicity have been quantified to create reactivity scales that explain why some atoms or molecules are more reactive than others. Most noteworthy is the work by Mayr and co-workers, who experimentally studied the reactivity of organic molecules that led to the Mayr-Patz equation;