Identify the elements correctly shown by decreasing radii size. N3to N S->S2- N>N3- Cu2+>Cu+ K+>K

The correct answers are: Cu2+ > Cu+ K+ > K

Explanation

• Option 1: N3-> N
  Anions are larger than their neutral atoms because they have more electrons than protons, which decreases the effective nuclear charge and increases electron-electron repulsion. Therefore, N3- is larger than N. So Option 1 is incorrect.
• Option 2: S-> S2-
  Anions are larger than their neutral atoms because they have more electrons than protons, which decreases the effective nuclear charge and increases electron-electron repulsion. Therefore, S is smaller than S2-. So Option 2 is incorrect.
• Option 3: N > N3-
  Anions are larger than their neutral atoms because they have more electrons than protons, which decreases the effective nuclear charge and increases electron-electron repulsion. Therefore, N is smaller than N3-. So Option 3 is incorrect.
• Option 4: Cu2+ > Cu+
  Cations are smaller than their neutral atoms because they have fewer electrons than protons, which increases the effective nuclear charge and decreases electron-electron repulsion. For the same element, the higher the positive charge, the smaller the ion. Therefore, Cu2+ is smaller than Cu+. So Option 4 is correct.
• Option 5: K+ > K
  Cations are smaller than their neutral atoms because they have fewer electrons than protons, which increases the effective nuclear charge and decreases electron-electron repulsion. Therefore, K+ is smaller than K. So Option 5 is correct.

Notice

This question focuses on understanding the periodic trends related to atomic and ionic radii. The core concept here is how the size of an atom or ion changes across a period and down a group in the periodic table, and how ionization affects size. To correctly answer this, you need to consider two main factors: the number of electron shells and the effective nuclear charge. As you move down a group, the number of electron shells increases, leading to larger radii. Across a period, the number of protons increases, pulling the electrons closer and thus decreasing the atomic radius. For ions, cations (positive ions) are smaller than their parent atoms because electrons have been removed, increasing the effective nuclear charge per electron. Anions (negative ions) are larger because electrons have been added, increasing electron-electron repulsion and decreasing effective nuclear charge per electron. Therefore, to evaluate the given trends, compare the positions of the elements in the periodic table and the charges of the ions. =