What does it mean when atoms are sticking to each other ?
Couper was the first to use lines between atoms , in conjunction with the older method of using brackets , to represent bonds , and also postulated straight chains of atoms as the structures of some molecules , ring - shaped molecules of others , such as in tartaric acid and cyanuric acid In later publications , Couper ’s bonds were represented using straight dotted lines ( although it is not known if this is the typesetter ’s preference ) such as with alcohol and oxalic acid below:In 1861 , an unknown Vienna high - school teacher named Joseph Loschmidt published , at his own expense , a booklet entitled " Chemische Studien I " , containing pioneering molecular images which showed both " ringed " structures as well as double - bonded structures , such as:Loschmidt also suggested a possible formula for benzene , but left the issue open .