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標題: maths +ｃｈｅｍ既問題．． [打印本頁]

作者: 小霞的fans 時間: 30/9/2008 04:18 PM
標題: maths +ｃｈｅｍ既問題．．
我想問giant ccovalent structures 同simple molecular structures 究竟有咩分別..
我真係唔明個mis up乜 -.-...

=================分隔線==========================
數學一題!
for the following equations,
1.find the discriminant

x^2+px-1 ..

我都唔知p個數字係乜 .. 點用b^2-4ac 計到個discriminant

作者: orb 時間: 30/9/2008 05:43 PM

原帖由 小霞的fans 於 30/9/2008 04:18 PM 發表

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我想問giant covalent structures 同simple molecular structures 究竟有咩分別..
我真係唔明個mis up乜 -.-...

=================分隔線==========================
數學一題!
for the following equations,
1.find the discriminant

x^2+px-1 ..

我都唔知p個數字係乜 .. 點用b^2-4ac 計到個discriminant

Giant covalent structure = 一個compound裡面有很多covalent bonding
Simple molecular structure = 一個compound裡面有較少covalent bonding / compound和compound互相聯繫的是較弱的van der Waal's Force

For "x^2+px-1"
D=p^2+4
如果冇比p你,就咁寫p^2+4就得

作者: abc666 時間: 30/9/2008 06:59 PM
補充
Giant covalent structure is substance that the whole structure bonded by covalent bonding(except graphite)
it is hard,non-conductor of electricity,high m.p. and b.p.
e.g.diamond

simple molecular structure is substance that is made up of many discrete molecules. there are covalent bondings between atoms in a molecule and the molecules are linked by weak Van der Waal's Force
it is soft,non-conductor of electricity,has low m.p. and b.p.
e.g. carbon dioxide

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