Discuss Question - AllPreviousYears

Correct Answer: A. Cations decrease in size and anions increase in size across a period.
Explanation: The ionic radius represents the distance from the nucleus to the outermost electrons of an ion. As you move across a period from left to right, the atomic number increases, which means the number of protons in the nucleus increases. This higher nuclear charge exerts a stronger pull on the electron shells, causing the size of cations to decrease. When transitioning to anions within the same period, these ions are significantly larger than the preceding cations because they have gained electrons; however, their size also tends to decrease as the nuclear charge continues to increase across the remaining p-block elements. Therefore, the most accurate description is that cations decrease in size and anions increase in size relative to cations across a period, though both generally follow a downward trend in radius as the effective nuclear charge increases.

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