7. explain why rubidium (rb) has a smaller ionization energy than iodine (i).

Brief Explanations:

Ionization energy depends on effective nuclear charge and atomic size. Rubidium is a metal in Group 1 with a large atomic size and low effective nuclear - charge on outer electrons. Iodine is a non - metal in Group 17 with a smaller atomic size and higher effective nuclear charge pulling outer electrons more strongly. So, it is easier to remove an electron from rubidium, resulting in a lower ionization energy.

Answer:

Rubidium has a larger atomic size and lower effective nuclear charge on its outer electrons compared to iodine, making it easier to remove an electron from rubidium, thus having a smaller ionization energy.