In order to determine the type of bond between two atoms, we need to consider their electronegativities. Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond. The difference in electronegativity between two atoms determines the polarity of the bond.

In the case of HCl, the electronegativity of hydrogen is 2.20, while the electronegativity of chlorine is 3.00. The difference in electronegativity between hydrogen and chlorine is 0.80. This difference is large enough to create a polar covalent bond, where the electrons are shared unequally between the two atoms.

The hydrogen atom has a slight positive charge, while the chlorine atom has a slight negative charge. This polarity is what gives HCl its acidic properties. When HCl dissolves in water, the hydrogen atom donates its proton (H+) to the water molecule, forming H3O+ and Cl- ions.