Question

Given below are two statements: Statement-I: The correct order for radius is \[ \mathrm{Al > Mg> Mg^{2+} > Al^{3+}} \] Statement-II: Atomic size always depends on electronegativity. In the light of the above statements, choose the correct option.

• A. Statement-I and Statement-II are correct
• B. Both Statement-I and Statement-II are incorrect
• C. Statement-I is correct but Statement-II is incorrect
• D. Statement-I is incorrect but Statement-II is correct

Answer 1

The Correct Option is B

This question tests the understanding of the periodic table trends, particularly concerning the atomic and ionic radii, as well as the concept of electronegativity.

1. Statement-I Analysis:
   • The given order is: \(\mathrm{Al > Mg > Mg^{2+} > Al^{3+}}\).
   • The atomic and ionic radii depend on the position of the element in the periodic table and their charge states:
     • Aluminum (\(\mathrm{Al}\)) and Magnesium (\(\mathrm{Mg}\)) have larger atomic radii than their respective cations (\(\mathrm{Mg^{2+}}\) and \(\mathrm{Al^{3+}}\)) because the loss of electrons generally decreases the size of the electron cloud.
     • \(\mathrm{Mg}\) typically has a larger atomic radius than \(\mathrm{Al}\) because it is to the left in the periodic table (Group 2 vs. Group 13).
     • Among ions, \(\mathrm{Mg^{2+}}\) is generally larger than \(\mathrm{Al^{3+}}\) because the loss of more electrons (+3 charge) results in a much smaller ionic radius for \(\mathrm{Al^{3+}}\).
   • This makes the order incorrect because although \(\mathrm{Mg}\) is indeed larger than \(\mathrm{Al^{3+}}\), \(\mathrm{Mg}\) should also be larger than \(\mathrm{Al}\), which it is not.
2. Statement-II Analysis:
   • Electronegativity is the tendency of an atom to attract electrons towards itself in a chemical bond.
   • While electronegativity can influence atom size (as more electronegative elements tend to pull electrons closer), atomic size is primarily determined by the number of electron shells and effective nuclear charge.
   • Therefore, electronegativity alone does not universally determine atomic size, making this statement incorrect.

Both statements have been analyzed and found incorrect:

• Statement-I contains inaccuracies regarding the atomic and ionic radius order.
• Statement-II incorrectly assumes atomic size is always dependent on electronegativity.

Thus, the correct option is: Both Statement-I and Statement-II are incorrect.