Question

Choose the correct ascending order of ionization energy for Zn, Cu, Ag:

• A. Ag<Cu<Zn
• B. Zn<Cu<Ag
• C. Cu<Zn<Ag
• D. Zn<Ag<Cu

Hint:

Ionization energy increases across a period and decreases down a group, but transition metals show exceptions due to electron configuration.

Answer 1

The Correct Option is A

Step 1: Understanding ionization energies.
Ionization energy generally increases across a period from left to right and decreases down a group. Zinc (Zn), Copper (Cu), and Silver (Ag) are transition metals, but their ionization energies vary due to the electron configuration and relativistic effects.
Step 2: Explanation of the order.
- Ag (silver) has a relatively low ionization energy because of the relativistic contraction and the stability of its electron configuration.
- Cu (copper) has a higher ionization energy than Ag but lower than Zn due to its filled \( 3d^{10} \) subshell.
- Zn (zinc) has the highest ionization energy because its electron configuration is \( 3d^{10} 4s^2 \), which is stable and less likely to lose electrons.
Step 3: Conclusion.
Therefore, the correct ascending order of ionization energies is: \[ \text{Ag}<\text{Cu}<\text{Zn} \] which corresponds to option (A).

Answer 2

Step 1: Silver (Ag) has a surprisingly low ionization energy due to relativistic effects on its outer electron.

Step 2: Copper (Cu) has a higher ionization energy than Ag but less than Zn, because of its filled 3d¹⁰ shell.

Step 3: Zinc (Zn) has the highest, since its 3d¹⁰4s² setup is extra stable and holds onto its electrons more tightly.

Step 4: So the ascending order is Ag < Cu < Zn — option (A).

Answer 3

Elimination approach: An ordering that puts zinc first as the easiest to ionize can be ruled out, because zinc's compact, extra-stable 3d\(^{10}\)4s\(^2\) arrangement actually makes it the hardest of the three to ionize, not the easiest. An ordering that puts copper below silver can also be ruled out, since copper's single 4s electron is still held more tightly than silver's outer electron once silver's relativistic effects are accounted for. That leaves silver easiest, then copper, then zinc: Ag < Cu < Zn, option (A).