Here's a breakdown:
* Electronegativity: Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. Chlorine has a higher electronegativity than hydrogen.
* Polar Covalent Bond: When two atoms with different electronegativities form a bond, the shared electrons are pulled more strongly towards the more electronegative atom. This creates a partial negative charge (δ-) on the more electronegative atom and a partial positive charge (δ+) on the less electronegative atom.
* HCl molecule: In the HCl molecule, the shared electrons spend more time closer to the chlorine atom (due to its higher electronegativity). This creates a partial negative charge (δ-) on the chlorine atom and a partial positive charge (δ+) on the hydrogen atom. This uneven distribution of charge results in a polar covalent bond.
Therefore, the HCl molecule has a dipole moment, meaning it has a positive and a negative end, making it a polar molecule.
