Question: Who developed the theory  of chemical bonds and molecular orbitals?
About the article "Chemistry", section "Chemical structure".

Candidate passages:
In chemistry, valence bond (VB) theory is one of two basic theories, along with molecular orbital (MO) theory, that were developed to use the methods of quantum mechanics to explain chemical bonding.
It focuses on how the atomic orbitals of the dissociated atoms combine to give individual chemical bonds when a molecule is formed.
In contrast, molecular orbital theory has orbitals that cover the whole molecule. 
Valence Bond Theory (VBT) an early bonding theory that has developed into Modern valence bond theory.
VBT views bonds as weakly coupled orbitals with each atom sharing a valence electron in a manner governed by the octet or 18 electron rule.
Lewis structures are a representation of VBT's most basic bonding while molecular geometry is derived from orbital hybridization.
Orbital hybridization is often taught with VESPR Theory despite significant differences in the underlying theory.
Valence shell electron pair repulsion (VSEPR) Theory The simplest and most primitive of the theories currently taught.
Describes molecular geometry through the repulsion of electron fields which include bonds and lone pairs.
It does not require any application of orbital shape.
Crystal Field Theory (CFT) This approximation begins with the geometries of the d orbitals derived from quantum mechanics.
Ligands with their electron density are assumed to destabilize the metal d orbitals they interact with raising their energy while the remain d-orbitals drop in energy to balance the overall change in energy.
Ligand Field Theory (LFT) Considered a hybrid of CFT and MO Theory or simple an approximate application of MO Theory to transition metal complexes.
Molecular Orbital (MO) Theory A current and often applied model of molecular bonding.
MO Theory assumes that bonds are derived from a linear combination of atomic orbitals.
In this linear combination each pair of atomic orbitals involved in bonding results in a bonding and anti-bonding orbital.
The destabilized of orbitals of CFT are now seen as anti-bonding component of orbitals that have overall been stabilized through bonding interactions. 
 "Not to be confused with s-p mixing in Molecular Orbital theory.
See Molecular orbital diagram.
In chemistry, hybridisation (or hybridization) is the concept of mixing atomic orbitals into new "hybrid orbitals" (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory.
Hybrid orbitals are very useful in the explanation of molecular geometry and atomic bonding properties.
Although sometimes taught together with the valence shell electron-pair repulsion (VSEPR) theory, valence bond and hybridisation are in fact not related to the VSEPR model. 
In chemistry, molecular orbital (MO) theory is a method for determining molecular structure in which electrons are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule.
Because electrons are the fundamental constituents of matter involved in bonding, their involvement in bonding has been studied exhaustively by chemists.
Electrons are shared among individual atoms in a molecule to form covalent chemical bonds.
Generally, up to three bonds can form between atoms in a molecule.
Single, or sigma covalent bonds result from the interaction between the nuclei of two discrete atoms; multiple bonds then can result due to the additional formation of pi bonds between overlapping orbitals of like symmetries.
Electrons in sigma bonds are located between the nuclei, while electrons in pi bonds are delocalized in regions above and below the nuclei.
The spatial and energetic properties of electrons within atoms are fixed by quantum mechanics to form orbitals that contain these electrons.
While atomic orbitals contain electrons ascribed to a single atom, molecular orbitals, which surround a number of atoms in a molecule, contain valence electrons between atoms.
Molecular orbital theory, which was proposed in the early twentieth century, revolutionized the study of bonding by approximating the positions of bonded electrons—the molecular orbitals—as Linear Combinations of Atomic Orbitals (LCAO).
These approximations are made by applying the Density Functional Theory (DFT) and Hartree–Fock (HF) models to the Schrödinger equation.MO theory applies the wavelike behavior of electrons as predicted by quantum mechanics, in that electrons no longer deterministically are given defined coordinates, but rather are given probable locations according to the mathematical wavefunctions defining all the possible positions of the electrons.
These wavefunctions, or electron eigenstates, quantitatively describe the atomic orbital basis in which an electron temporarily can reside.
Molecular orbitals result from the mixing of these atomic orbitals.
In this theory, each molecule has a set of molecular orbitals, in which it is assumed that the molecular orbital wave function "ψj" can be written as a simple weighted sum of the n constituent atomic orbitals "χi", according to the following equation: formula_1  
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.