The ions Sc³⁺, Mn³⁺, and Cr³⁺ when arranged in the increasing order of their ionic radius, follow the order _____. A) Sc³⁺

Question

The ions Sc³⁺, Mn³⁺, and Cr³⁺ when arranged in the increasing order of their ionic radius, follow the order _____. A) Sc³⁺ < Mn³⁺ < Cr³⁺ B) Cr³⁺ < Mn³⁺ < Sc³⁺ C) Mn³⁺ < Cr³⁺ < Sc³⁺ D) Cr³⁺ < Sc³⁺ < Mn³⁺ E) Sc³⁺ < Cr³⁺ < Mn³⁺

Quizplus · Accepted Answer

The trend in ionic radii is generally determined by the effective nuclear charge (the number of protons in the nucleus) and the electron configuration of the ion. As we move from left to right across a period in the periodic table, both the effective nuclear charge and the number of electrons in the outermost shell increase, resulting in a smaller ionic radius.

In this case, Sc, Mn, and Cr are all transition metals that are located in the same period of the periodic table (row 4). Therefore, the trend in ionic radii is largely determined by the effective nuclear charge of each ion.

Sc3+ has 21 protons in its nucleus, Mn3+ has 25, and Cr3+ has 24. Therefore, the effective nuclear charge increases in the order Sc3+ < Cr3+ < Mn3+. This suggests that the trend in ionic radii should be Mn3+ < Cr3+ < Sc3+ with Mn3+ having the smallest ionic radius and Sc3+ having the largest ionic radius.

Since the question is asking for the trend in increasing order of ionic radius, we need to reverse the trend we just found. Therefore, the correct answer is that the trend in ionic radii for Sc3+, Mn3+, and Cr3+ is Sc3+ < Cr3+ < Mn3+.

The Ions Sc3+, Mn3+, and Cr3+ When Arranged in the Increasing

The Ions Sc³⁺, Mn³⁺, and Cr³⁺ When Arranged in the Increasing