原帖由 比超仔 於 26/1/2008 06:20 PM 發表 
甚麼是antibonding electrons&bonding electrons...
比些例子我最好
例如N≡N ...
其中既no. of antibonding electrons&bonding electrons係幾多...
MO theory與Wave function有關，我沒有那邊的數學知識(只知是要用differential equation)
不過不緊的....知道orbital是由Wave function計出來就行了
Atomic orbital其實不是一個個圓形就算的，有sperical, dumbbell(ed) shape等，全是由wave function計出來的 (CE那個是簡化了做圓形)
普遍來說，electron都會先fill up 最低energy 的orbital 先，每個orbital可容納2粒electrons，且他們都會 spin in opposite direction 以減低repulsion
Molecular Orbital Theory is related to wave function and details of it require skills of differential equations.
In reality, atomic orbitals are NOT circular rings, they are of 3D geometry and have various shape like spherical and dumbbell(ed) shape; they can be interpreted from the wave function.
In general, electrons will fill up orbitals with lower energy, and an orbital can hold 2 electrons at maximum. The 2 electrons should spin in opposite directions to minimize repulsion.
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用最簡單的H2為例子：
Bonding orbital(σ) is formed by the addition of two wave functions.
Antibonding orbital(σ*) is formed by the subtraction of two wave functions.
()中的atomic 或molecular只是用來分清是哪種orbital.....平常沒必要的話可免掉
第一個orbital 是1s (atomic)orbital，H atom中的那一粒electron會occupy 1s (atomic)orbital
我們知H2 是covalent molecule，所以當兩粒H atom react時，electron不會只留在其中一個H那邊，而是shared. 所以有需要去用另一個方法表達在H2中的electrons.
兩個H的orbital 加起來及減起來時會分別出了σ1s 及σ1s* (用wave equation計的)
這兩個σ叫Molecular orbital(s), 有*的是antibonding, energy較高，所以放在1s的上面；σ1s比1s的energy 低，所以位置較低(如圖)
The first (atomic) orbital is 1s. So, the only electron in an H atom will occupy the 1s (atomic) orbital.
Since H2 is a covalent compound, when two H atom reacts, electron would be shared among the two atom instead of staying in one of the hydrogen.
For this reason, we need to use the MO theory to describe the electrons in the H2molecule.
When the two 1s orbitals in the two H atoms add up and subtract, σ1s and σ1s* would be determined. ( Determined by wave function)
These two σ are the Molecular orbital(s). The one with * is the antibonding orbital which is of higer energy, so it would be placed above 1s. σ1s is of lower energy than 1s, so it is placed under 1s(as shown in the picture).
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兩則的H 是指要react的兩個H atom，中間的H2可理解為product
由於物質都想處於較低的energy狀態(Lower energy, more stable)，所以他們會fill up σ1s先，而箭咀亦因要opposite spin而變為相反
Fill 完σ1s後，，兩個H atom的2粒electron已用完~不能fill σ1s*
Bond Order = (bonding electron - antibonding electron) /2
= (沒星的orbital中的electron量 - 有星的orbital中的electron量) /2
= (2-0) /2
= 1
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離題很遠了XD......看完不明就無視吧XD
Plus:
對了...CE及AL的在別人叫你畫H2或其他molecules 時不要送上面的東東給他們......兩個syllabus都沒要求學MO theory的....被扣分可別找偶 | 
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