Chemistry question

Question

Which ion has the largest radius?

(A) CI-

(B) F-

(C) K+

(D) Ca2+

could you explain which option is the correct answer?

Answer 1

Answer: (C) K+

Explanation: atomic radius increases going from left to right across a period and it increases going down a group. The anion (negative charged ion) is always larger than the neutral parent. The cation (positive ion) is always smaller than the neutral parent.

The size in decreasing order is as follows:

K⁺ > Ca²⁺ > Cl^- > F^- (K⁺ the largest, F^- the smallest)

Further explanation has to do with effective nuclear charge and electron repulsion, but that may beyond the scope for this question.