[T]he analogies between the two systems are striking. Just as Panini found that the phonological patterning of sounds in the language is a function of their articulatory properties, so Mendeleev found that the chemical properties of elements are a function of their atomic weights.

Like Panini, Mendeleev arrived at his discovery through a search for the “grammar” of the elements (using what he called the principle of isomorphism, and looking for general formulas to generate the possible chemical compounds).

Just as Panini arranged the sounds in order of increasing phonetic complexity (e.g. with the simple stops k,p… preceding the other stops, and representing all of them in expressions like kU, pU) so Mendeleev arranged the elements in order of increasing atomic weights, and called the first row (oxygen, nitrogen, carbon etc.) “typical (or representative) elements”.

Just as Panini broke the phonetic parallelism of sounds when the simplicity of the system required it, e.g. putting the velar to the right of the labial in the nasal row, so Mendeleev gave priority to isomorphism over atomic weights when they conflicted, e.g. putting beryllium in the magnesium family because it patterns with it even though by atomic weight it seemed to belong with nitrogen and phosphorus. In both cases, the periodicities they discovered would later be explained by a theory of the internal structure of the elements.