Question

As the elements of group 3 are considered in order from top to bottom, what happens to the first ionization energy of each successive element?

a. It increases.
b. It decreases.
c. It remains constant.
d. It fluctuates.

Answer 1

The first ionization energy of Group 3 elements decreases as you move from top to bottom due to the increasing atomic size and the reduced electrostatic pull on the valence electrons by the nucleus.

Step-by-step explanation:

As we consider the elements of Group 3 from top to bottom, the first ionization energy of each successive element decreases. This trend can be explained by the increasing size of the atoms down the group. The valence electrons in a larger atom are farther from the nucleus and are not held as tightly, which makes it easier for these electrons to be removed, resulting in lower ionization energy.

Ionization energy is indicative of the strength of electrostatic interactions between the nucleus and valence electrons. Thus, as the atomic size increases down a group, the ionization energy decreases because the outermost electrons experience a lesser pull from the nucleus.

Moreover, within a period, ionization energy will generally increase due to increasing nuclear charge and the same number of energy levels, thereby increasing the pull on the electrons. However, this is specific to trends across a period rather than down a group, which is the case for Group 3 elements going from top to bottom.