A
chemical structure includes
molecular geometry,
electronic structure and
crystal structure of
molecules. Molecular geometry refers to the spatial arrangement of
atoms in a
molecule and the
chemical bonds that hold the atoms together. Molecular geometry can range from the very simple, such as
diatomic oxygen or
nitrogen molecules, to the very complex, such as
protein or
DNA molecules. Molecular geometry can be roughly represented using a
structural formula. Electronic structure describes the occupation of a molecule's
molecular orbitals.
The theory of chemical structure was first developed by
Aleksandr Butlerov, which stated that the chemical compounds are not a random cluster of atoms and functional groups but structures with definite order formed according the
valency of the composing
atoms. Other important contributors were
Archibald Scott Couper and
Friedrich August Kekule.