Considering the periodic trend in successive ionization energies, which of the following elements is most likely to form an ion with the greatest positive charge before a dramatic increase in ionization energy occurs?

• A. Aluminum (Al)
• B. Potassium (K)
• C. Magnesium (Mg)
• D. Sodium (Na)

Answer: (A)

Verified step by step guidance

1. Understand that successive ionization energies refer to the energy required to remove electrons one after another from an atom. Typically, removing valence electrons requires less energy, but once you start removing core electrons, the ionization energy increases dramatically.
2. Identify the electron configurations of the given elements to determine how many valence electrons each has: Sodium (Na) has 1 valence electron, Magnesium (Mg) has 2, Aluminum (Al) has 3, and Potassium (K) has 1 valence electron in a new shell.
3. Recognize that the greatest positive charge an element can form before a large jump in ionization energy corresponds to the number of valence electrons it can lose easily. This is because removing core electrons requires much more energy.
4. For each element, consider the number of valence electrons that can be removed with relatively low ionization energy: Na can lose 1 electron, Mg can lose 2, Al can lose 3, and K can lose 1.
5. Conclude that Aluminum (Al), with 3 valence electrons, is most likely to form an ion with the greatest positive charge (+3) before a dramatic increase in ionization energy occurs, compared to the other elements listed.