Structural chemistry

Structural chemistry is a part of chemistry and deals with the connectivity and shape of individual chemical species, which includes molecules, ions, and polymers. Structure is central to understanding the behavior of chemical species, so the topic is foundational. Structure is integrated into the major branches of chemistry, i.e. inorganic chemistry and organic chemistry. One indicator of the centrality of structural chemistry, many of the Nobel Prize in Chemistry have been awarded for structural insights or techniques important for determining structure.

A chemical structure of a molecule is a spatial arrangement of its atoms and their chemical bonds. Its determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of atoms in a molecule and the chemical bonds that hold the atoms together and can be represented using structural formula and by molecular models; complete electronic structure descriptions include specifying the occupation of a molecule's molecular orbitals. Structure determination can be applied to a range of targets from very simple molecules (e.g., diatomicoxygen or nitrogen) to very complex ones (e.g., such as protein or DNA).

In chemistry, "structure" takes distinct meanings depending on the length scale and time scale. With respect to length scales, on a local level, structure refers to interatomic distances and angles. On a larger length, symmetry and periodicity are important descriptors.