Which of the following elements has the highest third ionization energy?
Correct answer: B. Magnesium
- A. Sodium
- B. Magnesium
- C. Aluminum
- D. Silicon
Explanation
The third ionization energy refers to the energy required to remove the third electron from an atom. Magnesium, with an electronic configuration of [Ne] 3s², when it loses two electrons, becomes a stable neon-like [Ne] configuration. Removing a third electron from this stable configuration requires a significantly higher amount of energy. In contrast, sodium and aluminum do not achieve a stable noble gas configuration after the removal of three electrons, and silicon's third electron is removed from a less stable configuration, making their third ionization energies lower than that of magnesium.
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About Periodic Properties and Trends
Periodic properties arise from electron configuration and effective nuclear charge, producing trends in atomic and ionic radius, ionization energy, electron affinity, electronegativity, metallic character and reactivity. Comparisons run across periods and down groups, with attention to common exceptions. The topic also relates these trends to the behavior of s-block and p-block elements.
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