The polar character of covalent bond

A polar bond can be defined as a covalent connection with a particular shape. It is also the dividing line between the development of a pure covalent bond and the formation of an ionic bond. However, a polar covalent bond is a link that exists between two atoms and is made up of electrons that are not uniformly distributed. Due to this condition, the molecules tend to have an electrical dipole moment, with the two ends slightly positive or negative.

The numerous forms of covalent bonding are determined mainly by electronegativity. An atom’s tendency to draw a shared pair of electrons towards itself is known as electronegativity. It doesn’t have any units because it’s only a tendency. A polar covalent bond is a covalent link established between two atoms in a molecule with an electronegativity difference.

Types of covalent bond

Depending on the electronegativity of the combining atoms, two types of covalent bonds exist.

Nonpolar covalent bond

When two atoms of the same element make a covalent connection, the shared electron pair will be exactly halfway between them, implying that the atoms will evenly share the electrons. The resulting molecule will be electrically symmetrical, meaning that the negative charge’s centre will coincide with the positive charge’s centre. A nonpolar covalent bond is a name given to this sort of covalent link. H₂, O₂, Cl₂, and other chemicals have nonpolar covalent bonding.

Polar covalent bond

A polar covalent bond is a link formed between two atoms that are different in their electron affinities. When two atoms of other elements make a covalent bond, the bonding pair of electrons will lie more towards the atom having a higher affinity for electrons.

The atom with a higher affinity for electrons gets a slight negative charge, while the atom having a lower affinity for electrons develops a small positive charge. Polar molecules are the name for these types of molecules.

Polar covalent compounds are those that have polar bonds in them. Polar compounds do not conduct electricity in their pure state but produce conducting solutions when dissolved in polar solvents.

Explanation of the polar covalent bond

Polar covalent bonds are created when two non-metal atoms with differing electronegativities. Consider A and B, who have a chemical connection between them and an electronegativity difference that is not equal to zero. The electrons that establish a relationship between A and B migrate towards the electronegative B.

Then B receives a partial charge and achieves A as H – Cl. A becomes partially charged, with two charges (poles form and the molecule is called a dipolar molecular, dipole, or polar covalent molecule). This molecule’s shared pair of electrons moves towards a chlorine atom with a strong electronegative charge. The H atom receives a partial positive charge, while the Cl atom receives a partial negative charge, resulting in the formation of a dipole.

Properties of the polar covalent compounds 

• These chemicals can exist as solids because of the more potent force of interactions.
• These compounds’ melting and boiling temperatures are higher than those of nonpolar compounds.
• They conduct electricity in the solution state because of the mobility of ions.
• In polar solvents like water, they are quite soluble.

Dipole moment

Dipole moment: A physical quantity called dipole moment can explain the polarity of a covalent bond.

The dipole moment equals the product of charge and charges separation distance. Debye or esu cm is the unit of measurement.

Dipole moment = e X d (esu cm)

Where d denotes the distance between the charge and the bond length.

e stands for the electronic charge.

What elements can form polar covalent bonds?

Polar covalent bonds arise when the electronegativity gap between two non-metal atoms is large enough. The electronegativity values are somewhat different because the bonding electron pair is not uniformly shared amongst the atoms. Polar covalent bonds are generated between hydrogen and any other non-metal in most cases.

Metals and non-metals have such a vast disparity in electronegativity levels that they form ionic connections with one other.

Molecules with polar covalent bonds examples

Consider the hydrogen chloride molecule’s covalent link between one hydrogen atom and one chlorine atom. A polar covalent bond exists here. Chlorine has a higher electronegative potential than hydrogen. The electron bond pair will be attracted to the more electronegative chlorine atom. There will be no bond pair of electrons halfway between the hydrogen and chlorine atoms. The bond pair of electrons will be closer to chlorine atoms than to hydrogen atoms. As a result, the chlorine atom acquires a partial negative charge, whereas the hydrogen atom acquires a partial positive charge. The hydrogen chloride molecule turns polar and has a dipole moment.

Ammonia molecules have a polar covalent link between the nitrogen and hydrogen atoms. A polar covalent linkage exists between the oxygen and hydrogen atoms of the water molecule.

The electronegativity difference between two atoms of the same element is zero when they form a covalent connection, making it a nonpolar covalent bond. A nonpolar covalent bond exists between two hydrogen atoms in a hydrogen molecule. A nonpolar covalent link exists between two chlorine atoms in a chlorine molecule.

Conclusion

A polar bond is a chemical bond between two atoms and consists of electrons scattered unevenly. As a result, the molecules tend to have an electrical moment, with the two ends being slightly positive or negative. The many forms of covalent bonds are determined mainly by electronegativity. An atom’s tendency to attract a shared pair of electrons to itself is known as electronegativity. A polar chemical link is produced when two atoms with different electronegativity establish a chemical connection. Polar covalent bonds are formed between non-metallic atoms with high electronegativities differences. We have understood the polar character of the covalent bond with the help of some examples.