Question

Which among the following has the least second ionization energy?

• A. Al
• B. Si
• C. P
• D. S

Hint:

The second ionization energy is generally lower for elements that are one electron away from achieving a stable noble gas configuration.

Answer 1

The Correct Option is B

Step 1: Understanding Second Ionization Energy.
The second ionization energy is the energy required to remove the second electron from an ion. The ionization energy generally increases as we move across a period and decreases as we move down a group. However, the ionization energy can also be influenced by the electronic configuration of the element.
Step 2: Analyzing the Options.
- (A) Al: Aluminum has a relatively low second ionization energy, but its electron configuration is more stable after the first ionization.
- (B) Si: Silicon has a relatively lower second ionization energy because after the first ionization, it is left with a stable configuration closer to a noble gas, making it easier to remove the second electron. This gives Si the lowest second ionization energy.
- (C) P: Phosphorus has a higher second ionization energy compared to silicon due to its higher effective nuclear charge and more stable electron configuration.
- (D) S: Sulfur has a higher second ionization energy than Si, as it has a more tightly held second electron due to its atomic structure.
Step 3: Conclusion.
The correct answer is (B) Si, as it has the least second ionization energy among the given elements.