原帖由 dolphin_ice 於 4/3/2008 08:41 AM 發表 
sigma bond 和 pi bond 到底是什麼一回事?
2樣的性質有何不同? 什麼情況下會是sigma, 什麼情況是pi?
有人可以給予我一些資料嗎?
另外, 有關s,p subshell合拼成sp subshell:
1. Why does it happen?
2. 有何性質?
3. 有多少種類?
4. sp1 sp2 sp3 到底是什麼? 有sp4嗎? What is the difference?
5. p subshell應該有分x, y, z 3 種, xyz會影響sp合体嗎?
sigma bond : end-to-end overlap of orbitals
pi bond: sideway overlap of orbitals (in other words, side-to-side overlap)
所有molecule也有sigma, 只有double/ triple bond時,才會有pi 的出現
下面是用ethene 做example, 我只集中看C=C
綠色的是pi, 黑色是sigma(包括鉛筆)
左面的綠色dash line是指 attraction看不到圖可按我
下link是N2的example, 由於是由別的書取來的,還是hide一下好了:hug:
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Using CH4 as an example,
1. s is spherical, p is dumbbell shape. The three p orbitals are 90 degree to each other.
If the C atom just simply bond to hydrogen without hybridization, the bond angles would be 90 degree between three H atoms (bond to p) and one H atom is bonding with the s electron in somewhere.
(If you can imagine a picture of it, you will know it looks very weird and unstable.)
However, by experiments, we know thatallbond angle are 109.5 degree (i.e.equal). The hybridization model explains the reason for 109.5 degree.
With hybridization, sp3 in CH4 as example, the2s orbital mix withthree 2p orbitalsin the way the diagram expressed in. 看不到圖可按我
留意一下promotion 與hybridization之間的energy, 它們(2p VS sp3)的energy是有分別的，sp3較stable
After hybridization, the energy of the four orbitals are equal and able to form 4 bonds withequal bond angle.
2.
不解性質指甚麼，但我想"equal" 是你要的字眼
4.
這問其實應放在3.前
s = s orbital
p = p orbital
d = d orbital
上面的superscript = number of that orbital
e.g. sp3 = 由1個s mix 3個p
sp3d2 = 1個s + 3個p + 2個d mix起
沒有sp4的，由wave equation計出來，最多只有3個p
3.
最common及我們現在會用的是 sp, sp2, sp3, dsp3 (OR sp3d), d2sp3 (OR sp3d2)
3rd row element才會用到d orbital, Or chem 主要看 sp, sp2 及sp3 ( carbon嘛:hug: )
5.
三者的分別只在於方向，以我暫時學的是沒有影響的
一般寫時sp2都是留下2pz unhybridized. 原因是 z 比y及x後
很想有像以前一樣有superscript及subscript功能
[ 本帖最後由 fish 於 4/3/2008 11:22 AM 編輯 ] |
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