Q86 · CSIR-NET Chemistry, June 2012

Paper: CSIR-NET June 2012 · Subject: Physical Chemistry · Chapter: Quantum Chemistry · Topic: Huckel MO Theory · Marks: 2 · Difficulty: Medium

Using Huckel molecular orbital approximation, the two roots of secular equation of ethane are

(a)$\alpha+\sqrt{2} \beta, \alpha-\sqrt{2} \beta$

(b)$\alpha+\beta, \alpha$

(c)$\alpha+\beta, \alpha \beta$

(d)$\alpha+2 \beta, \alpha-2 \beta$

Answer

Answer: B ✓ checked by 4AB · confidence high

The source book printed no answer; this one was worked out and checked — see the explanation.

Explanation

Ethylene's 2×2 Hückel determinant (α − E)² − β² = 0 gives E = α + β (bonding) and α − β (antibonding).

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