In HCl-HCl, the hydrogen-chlorine link is a polar covalent bond. It is produced when two atoms share an electron pair.
When atoms with various electronegativities share electrons in a covalent link, the result is a polar covalent bond. Think about the molecule of hydrogen chloride (HCl). In order to generate an inert gas electron configuration, each atom of HCl needs an additional electron. Despite having a stronger electronegativity than hydrogen, the chlorine atom cannot remove an electron from hydrogen due to its inability to attract electrons. As a result, a polar covalent bond in hydrogen chloride has an unbalanced distribution of bonding electrons.
The heat energy breaks down the bonds between the molecules of the solid so the molecules become looser. Further hearing of the liquid causes the bonds to be broken down and the molecules will move further apart.
