delocalized electrons are electrons which are not bonded together, graphite can conduct electricity due to the free electrons(delocalized)
the electrons can move together and forms a special intermolecular force called instantaneous dipole-induced dipole attraction* between 2 layers.
but, instantaneous dipole-induced dipole attraction is one kind of weak van der Waals' forces, this attraction is not a main point for bonding,
in general cases, each carbon atom in a graphene has only 3 single bonds without any double bonds.
*instantaneous dipole-induced dipole attraction is beyond your standard, you may not need to understand now, there is no contradiction in your questions.
you can now consider the attraction between 2 graphenes is called van der Waals' force delocalized electrons are electrons which are not bonded together, graphite can conduct electricity...
-終場ソ使者- 發表於 17-11-2010 21:37 http://www.nakuz.com/bbs/images/common/back.gif
查實有冇strong van der waals' force....
好似e加次次都係講親都一定係weak van der waals' force.... van der Waals' force係intermolecular forces既一個統稱
係有strong既,eg: hydrogen bond,permanent dipole-permanent dipole attraction(is a polar bond),
不過你地而家唔洗知係咩黎住,microscopic world II會講
delocalized electrons係free electrons黎 Matter forms bond to make it become more stable.
carbon既世界入面,有一種比form死bond 更強既現象,叫做resonance. 即係你阿sir所講既情況.
好似Benzene咁,每粒C都要form 4個bond,就會出現圖中左邊既arrangement,但係個pi bond (double bond 中較弱既bond) 既電子可以跳黎跳去,變成圖中右邊咁既arrangement,所以就係所講既double bond有時變single bond, single bond 有時變double bond 既情況.
個pi bond跳黎跳去,就好似form左一個會轉既圈,呢個咁既樣比圖中左邊右邊都更穩定.
Bond其實係electons pairs,可以郁既bond => delocalized electrons
From wiki, Benzene
http://upload.wikimedia.org/wikipedia/en/e/e8/Benzene_resonance.png
http://upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Benz4.png/100px-Benz4.png
不過有delocalized electrons唔代表可以conduct electricity....我未聽過benzene可以通電...
graphite既resonant應該同benzene有分別. Matter forms bond to make it become more stable.
carbon既世界入面,有一種比form死bond 更強既現象,叫做 ...
【YU】 發表於 20-11-2010 01:15 http://www4.nakuz.com/bbs/images/common/back.gif
pi bond係咩黎-.-
補充番,fullerenes(eg:C60 buckminsterfullerene)都有delocalized electrons,不過佢唔能夠通電,因為佢只係一個simple molecular structure黎 本帖最後由 【YU】 於 20-11-2010 17:36 編輯
諗返通.... Benzene, C60 既 delocalized electrons 都限制左喺1個molecule入面.
而graphite既structure係六角蜂巢陣,layer by layer,delocalized electrons可以喺layer與layer之間既空間自由活動,所以:
如果apply 電壓 parallel to layers,electrons係可以喺層layer上面drift黎通電
如果apply 電壓 perpendicular to layers,因為electons俾layer隔開,所以通唔倒電.
http://upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Graphite-layers-top-3D-balls.png/120px-Graphite-layers-top-3D-balls.png
double bond兩個bond係有分別,pi bond 係 double bond 入面較弱既bond. 當你學到hybridization既時候,就會知係咩黎.
http://en.wikipedia.org/wiki/Double_bond
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