Chemical Bonding-Concept of Covalent Bond

A chemical bond formed between the atoms due to the sharing of electrons between them is called a covalent bond. The pair of electrons that form a part of this sharing is called shared pairs or bonding pairs. The bond formed because of the attractive and repulsive forces of the atoms, when they share electrons, is called covalent bonding. It basically is the interatomic linkage that leads to the sharing of electrons between the atoms. The binding occurs due to the presence of electrostatic attraction of the nuclei of their elements. The energy required for the binding and sharing to take place should be lower as compared to that of widely separated atoms as it becomes easy for the atoms to share the electrons and form a bond.

Covalent Bonds definition

The easiest way to understand what a covalent bond is that it is a bond formed by an attractive force between atoms. The electrons are shared. This type of bonding occurs between two atoms of an equivalent element or elements of one another within the table. This type of bond can generally be seen among non-metals, but it also occurs between metals and nonmetals. Metals alone never form covalent bonds.

If atoms have the same electronegativities, i.e. They have the same affinity for electrons, covalent bonds are most likely to occur. Molecules with covalent bonds include inorganic substances like hydrogen, nitrogen, chlorine, water and ammonia, alongside all the organic compounds.

In the structural representation of compounds, the bonds are shown with the help of lines between the atoms. A single line indicates a single covalent bond between two atoms, double lines means a double covalent bond between two atoms, and triple lines mean a triple covalent bond is formed in carbon monoxide.

Lewis evaluation of Covalent Bond

The octet rule or the law of octaves is a principle of chemical bonding that states that the outermost (valence) electrons of atoms in a pure chemical compound must occupy spaces in the electronic structure that are as far away from each other as possible. The law was formulated by chemist Gilbert N. Lewis in 1916 and is an extension of the concept of valence shell electron pair repulsion (VSEPR).

The law is applied to any elements in the same group in the periodic table. The most stable arrangement for two atoms is to share two electrons, forming a single bond. The next most stable arrangement is to share four electrons, forming two bonds. The final, least-stable arrangement of eight electrons is achieved when each atom has eight, hence the term “octet”, from the Latin octāvus for ‘eighth’.

In each case, the central dot represents the central atom, in this case, hydrogen or oxygen. There are dots around the perimeter to indicate covalent bonds. On either side of each dot is an arrow representing a lone pair—the chlorine atom has one lone pair and hydrogen has two.

All four dots have arrows pointing toward them. This indicates that all four atoms have electron pairs that have been bonded to other atoms (a “bonding” interaction). In HCl, for example, this bond is between a chlorine atom and a hydrogen ion (H + ). The electrons from each bonding pair overlap to form what’s called a “covalent bond,” which takes its name from Latin for ‘shared’.

Characteristics of Covalent Bond

In a covalent bond, two atoms share an electron pair; each atom essentially takes responsibility for one of the pairs. The shared pair’s negative charge is then exactly cancelled by the positive charges in their nuclei.

The shared electron pair is like the third wheel in a romantic triangle: it makes both partners feel wanted. A shared electron pair is more stable than two electrons flying solo—it has lower energy. And when two atoms form a team to get that lower energy, they form a molecule—a covalent bond—and they are chemically bonded together.

Conclusion:

In this material, we discussed the covalent bond definition and types of covalent bonds in detail. In a covalent bond, two atoms share an electron pair; each atom essentially takes responsibility for one of the pairs. The shared pair’s negative charge is then exactly cancelled by the positive charges in their nuclei.

We also discussed how Lewis structures have contributed to the same.