Primordial chemistry from molecules to secondary cosmic microwave background anisotropies

The chemical history of the early Universe has strong consequences on the formation of the first bound objects and the spectrum of cosmic microwave background anisotropies. In this paper we investigate these questions through the creation of the primordial nuclei to the formation of the first atoms and molecules. Francesco Melchiorri influenced a large number of theorists on this new field of cosmochemistry. Some part of Francesco’s work will be largely mentioned and discussed.