In the formation of H₂ molecules from 2 H atoms placed at positions A and B, and separated by a distance rAB… · ABC26PH0145
Subject: Physical Chemistry · Chapter: Quantum Chemistry · Topic: Quantum Chemistry – General · Exam: CSIR NET 2013 · Marks: 2 · Difficulty: Medium
In the formation of $\mathrm{H}_{2}$ molecules from 2 H atoms placed at positions A and B , and separated by a distance $r_{AB}$, a part of special wavefunction is
(a)This is a covalent term and is important as $r_{AB} \rightarrow \infty$
(b)This is a ionic term and is important as $r_{AB} \rightarrow \infty$
(c)This is a covalent term and is important as $r_{AB} \rightarrow 0$
(d)This is a ionic term and is important as $r_{AB} \rightarrow 0$
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
φ_A(1)φ_A(2) + φ_B(1)φ_B(2) places both electrons on the same atom — H⁺H⁻ — so it is the ionic term. It matters at short r_AB (united-atom limit) and vanishes in importance as r_AB → ∞, where the covalent term describes two neutral atoms.