In chemistry, a Lewis structure is a 2D representation of a molecule on paper. It is used primarily to show the approximate relative positions of each atom in relation to the other atoms in the molecule, the topology of the covalent bonds linking them, and the allocation of electrons to the atoms in the molecule.
A number of heuristic rules (based mostly on the octet rule) can then be applied to work out the distribution of charge across the structure. This does not always produce correct results, but works in enough cases to make Lewis structures a useful tool in chemistry.
It was devised and named after G. N. Lewis.