Covalent Bonding - The Electronic Theory

(Localized Chemical Bonding) Covalent Bonding, The Electronic Theory - Structure and Bonding

ChemistryExplain provide notes about Structure and Bonding today we discuss “Covalent Bonding - The Electronic Theory” Organic Chemistry, Organic chemistry online course, Acs organic chemistry, Organic chemistry jobs

Organic chemistry is the chemistry of carbon compounds. This definition includes compounds like CO, C02, CS2, carbonates, cyanates, cyanides, etc. but they are usually described in textbooks of inorganic chemistry due to their greater resemblance with inorganic compounds. Organic chemistry is a very systematic subject which is based on the structures of molecules and their reactivity. The presence of covalent bonds is the characteristic of organic (carbon) compounds. This implies that most of the organic compounds are covalent compounds. Thus, the covalent bond is of chief importance in the study of organic chemistry.
For More Chegg Questions

• Inorganic Chemistry
• Organic Chemistry
• Physical Chemistry

Covalent Bonding

The Electronic Theory: It was based on the electronic structure of atoms. In 1916, G.N. Lewis (of the University of California) was the first to suggest that chemical combinations of atoms can take place through the covalent bond formation. A covalent bond is formed by sharing of electrons, each atom contributing one or more electrons to form the shared pair or pairs. In this way, each of the bonded atoms attains the stable electronic configuration of the nearest noble gas. The two bonded atoms are held together by a shared pair or pairs of electrons, i.e., covalent bond(s). The covalent bond formed by sharing of one electron pair is called a single bond (as in hydrogen and chlorine molecules), whereas that formed by sharing of two-electron pairs (as in oxygen molecule) and three electron pairs (as in nitrogen molecule) are called double and triple bonds, respectively. Double and triple bonds are collectively called multiple bonds. The structures in which the shared electron pair(s), as well as all the unshared valency electrons (non-bonding electrons) of bonded atoms, are shown by dots were first used by Lewis and they are known as Lewis structures. In Lewis structures, the symbol of the atom represents kernel (nucleus + electrons except for valency electrons) but not the only the nucleus. The electrons of the outermost shell of an atom are called valency (valence) electrons.

For More Chemistry Notes and Helpful Content Subscribe Our YouTube Chanel - Chemistry Explain

 (In HCI, hydrogen has two electrons in its valence shell and chlorine has eight electrons in its valence shell)

When a dash (-) is used in place of dots corresponding to each shared pair of electrons and the dots corresponding to all the nonbonding electrons are omitted, the structures of molecules are known as Couper structures (structural formulae) because he proposed such structures. For example, the Couper structures of covalent compounds like H₂, 0_2, and N₂ are depicted as follows :

The omission of the unshared valency electrons is the limitation of Couper structures. A widely used scheme for representing the structure of molecules uses Couper structures indicating all the unshared valency electrons by dots, such structures are also called as Lewis structures, for example :