[試題] 97下 王 瑜 化學鍵 期中考
課程名稱︰化學鍵
課程性質︰選修
課程教師︰王瑜
開課學院：理學院
開課系所︰化學系
考試日期（年月日）︰98/4/17
考試時限（分鐘）：100分鐘+10分鐘延長
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1.Work out the molecular orbitals of A2; write down electronic configuration,
bond order and magnetic property of B2, C2 and O2. Compare the bond order
and bond distance of NO, NO+ and NO-.
2.Describe the molecular orbitals (MO) of planar cyclo-H5 and -H6 in terms of
two fragments as H3 + H2 and H3 + H3.
3.Work out the MOs of CH4 in tetrahedral and seesaw shape (with a linear CH2
part) respectively; plot the orbital correlation and predict the geometry of
CH4, CH4(+), CH4(2+).
4.The π electron energy of butadiene is lower than that of cyclobutadiene,
but it is just the opposite for hexatriene and benzene case, explain. What
is the condition for aromaticity of planar cyclo-CnHn? Why? What is the res-
onance (delocalization) energy of benzene in terms of β, assuming α+βfor
ethylene? The orbital energy of cyclo CnHn, CnH(n+2) are as following:
Cyclo-CnHn: Ei = α+2βcos(2jπ/n) where j = 0, ±1, ±2,...
-2┌ __ ─ ≡
│ ─ ¯¯ ≡
-1│ ─ ─ ─ ≡
│ ─ __ ≡
0│─ ─ ─ __ ≡
│ ─ ≡
1│ ─ ─ __ ≡
│ ─ __ ≡
2└ ¯¯ ─ ≡
CnH(n+2): n 1 2 3 4 5 6 ∞
5.Given the orbital correlation diagram of AH2 between the linear and bent
case below; explain why the bent angle of H-A-H is 119, 92 and 92 for A =
Al, Si and P respectively. Predict the geometry of each dication AH2(2+).
(Figure: orbital correlation diagram of AH2 between the linear and bent case)
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