Cl and I would have very similar chemical and physical properties.
Work Step by Step
Chlorine (Cl) and iodine (I) are both in the same family of elements. They are both in Group VIIA of the periodic table, in the family of elements called the halogens. These elements are highly reactive because they have seven electrons in their outermost energy levels; these electrons are called valence electrons. Because of these seven electrons, the halogens, wanting to fill their outermost energy levels with eight electrons, tend to grab electrons from electron donors such as metals.