A Lewis structure of HCl, which shows that chlorine has 8 electrons and hydrogen has 2 electrons. 

    Hydrogen chloride is composed of one atom of hydrogen and one atom of chlorine. The hydrogen and chlorine atom are joined together by a single covalent bond. A covalent bond is when two atoms share a pair or pairs of valence electrons. In the hydrogen chloride compound, there are three unshared electron pairs around the chlorine atom. The chlorine atom has eight electrons in its outer shell and the hydrogen atom has two electrons. The percent composition of hydrogen in the hydrogen chloride molecule is 0.03%, and the percent composition of chlorine in the hydrogen chloride molecule is 97%. The percent composition by number for HCl is 50% of hydrogen and 50% of chlorine because the compound is a 1 to 1 ratio.