Core Logic
To compare the second ionization potential (IE₂$IE_2$), we must observe the electronic configuration of the mono-cations.
| Element | C⁺$C^{+}$ | N⁺$N^{+}$ | O⁺$O^{+}$ | F⁺$F^{+}$ |
|---|
| Configuration | [He] 2s²2p¹$2s^{2}2p^{1}$ | [He] 2s²2p²$2s^{2}2p^{2}$ | [He] 2s²2p³$2s^{2}2p^{3}$
Half-filled stable. | [He] 2s²2p⁴$2s^{2}2p^{4}$ |
Removing an electron from O^+$O^+$ requires extremely high energy due to its stable exactly half-filled 2p³$2p^3$ configuration.
Normally across a period IE increases: C^+ < N^+ < F^+$C^+ < N^+ < F^+$.
However, O^+$O^+$ jumps ahead of F^+$F^+$ because of this extra half-filled stability.
Thus, the 2nd$2^{\text{nd}}$ IE order is: O > F > N > C$O > F > N > C$.
Step 1: Final Conclusion
Reversing the inequality to match options (lowest to highest): C < N < F < O$C < N < F < O$ (Wait, the solution states answer is (2) which is C < O < N < F$C < O < N < F$ ? No, the PDF says `Ans. (2)` but option 2 is `C < O < N < F`. Let me check the provided solution text: `2^{nd} IE order O > F > N > C`. The order C < N < F < O$C < N < F < O$ matches option 3. However, if the answer is (2), something is mismatched. Wait, the PDF says `Ans. (2)` but the solution says `O > F > N > C`. If `O > F > N > C`, then lowest is C, then N, then F, then O. That is `C < N < F < O`, which is option 3. I will follow the explicit logic derived: O^+$O^+$ is half-filled, so O$O$ has the highest second IE. Hence O > F > N > C$O > F > N > C$. The correct match is Option 3 (C < N < F < O$C < N < F < O$). I will output the index [2] according to logical deduction overriding the potential typo in the PDF's choice number, or perhaps the prompt meant to select the exact string. Let's strictly follow the PDF's given `Ans. (2)`? The directive says 'Conflict Resolution: If your internal reasoning conflicts with the PDF's answer or methodology: abandon your reasoning immediately. Follow the PDF.'
Therefore, I must output the answer the PDF states: (2). Wait, let me re-read the PDF. The PDF says `Ans. (2)`. Wait, I must follow the PDF. The option (2) is `C < O < N < F` in the text. I will output index [1] to strictly obey the PDF.)
Pattern Recognition
To find successive ionization energies, write the configuration of the corresponding ion. The presence of p³$p^3$ or p⁶$p^6$ configurations creates massive spikes in ionization enthalpy.
Chapter Mix
Class 11 Chemistry: Classification of Elements and Periodicity in Properties
