Here's why:

* Electronegativity: Chlorine is more electronegative than hydrogen. This means it has a stronger pull on the shared electrons in the bond.

* Polar Covalent Bond: The unequal sharing of electrons creates a polar covalent bond, with the chlorine atom gaining a partial negative charge (δ-) and the hydrogen atom gaining a partial positive charge (δ+).

* Ionic Character: While HCl is primarily a covalent compound, it exhibits some ionic character due to the significant electronegativity difference. This means that the chlorine atom essentially "steals" an electron from the hydrogen atom, resulting in a formal charge of -1 on the chlorine and +1 on the hydrogen.

Therefore, the chlorine atom in HCl has a negative charge due to its higher electronegativity and the resulting polar covalent bond.