Here's why:

* Electronegativity trend: Electronegativity increases as you move across a period (from left to right) and decreases as you move down a group (from top to bottom) in the periodic table.

* Location: Chlorine is located above iodine in the same group (Group 17, halogens).

* Atomic size: Iodine is larger than chlorine due to the increased number of electron shells. The larger size means the outer electrons are further from the nucleus and less tightly held, leading to lower electronegativity.

Therefore, chlorine has a higher attraction for shared electrons in a bond compared to iodine.