Question

What type of bond involves the unequal sharing of electrons between atoms?

Answer 1

Hint: To solve this question we first need to know what kinds of bonds are formed by sharing of electrons between atoms. When in a molecule the valence electrons are shared between the atoms, a covalent bond is formed.

Complete answer:
When the electrons are unevenly distributed or are unequally shared, the bond formed is known as a polar covalent bond.
Polar covalent bonds are said to be the dividing line between ionic bonds and pure covalent bonds.
There exists an electronegative difference between the atoms of the molecule bonded by polar covalent bonds.
(The tendency of an atom to attract an electron which is shared towards itself is known as electronegativity.)
Usually, two non-metals that have different electronegativities form a polar covalent bond.
In the molecule bonded by a polar covalent bond, the more electronegative atom forms a partial negative charge whereas the less electronegative atoms form a partial positive charge. Due to these partial positive and negative charges on the atoms, the molecule develops some electrical dipole moment.
For example, in HCl, hydrogen atoms form a partial positive charge and chlorine atom forms a partial negative charge.
$H^{\delta +}-C{l}^{\delta -}$
Polar covalent compounds exist in the solid-state as they have greater forces of interaction. It has higher melting and boiling points than non-polar compounds and shows more conductivity of electricity and solubility in polar solvents.

Note:
It should be noted that when electrons are shared equally between two atoms, the bond formed is a nonpolar covalent bond. The electronegative differences between the atoms of the molecule bonded by non-polar covalent bonds are almost negligible.