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Topic: molecular shapes  (Read 6664 times)

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Maradona

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molecular shapes
« on: November 14, 2005, 06:45:53 PM »
Hellow, How do u tell what molecular shape a bond is, like linear, tetra etc..

for H2O for example i know how to draw it but i cant seem to figure out what shape it is
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Offline Donaldson Tan

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Re:molecular shapes
« Reply #1 on: November 14, 2005, 07:49:14 PM »
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Offline mike

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Re:molecular shapes
« Reply #2 on: November 14, 2005, 07:49:55 PM »
You must use the VSEPR theory (Valence Shell Electron Pair Repulsion). The interactions in order of repulsion (greatest to smallest) are:

lone pair - lone pair
lone pair - bonding pair
bonding pair - bonding pair

In general the molecule will take the shape that causes least interactions. Usually your choices are:

linear
V-shaped
trigonal planar
tetrahedral
pyramidal

I am presuming you can draw the dot structure for water (H2O). If you left it as a linear molecule you will notice that there is 90 degrees between the lone pairs and bonding pairs etc. A kind of tetrahedral arrangement of the lone pairs and bonding pairs around the O will produce a greater distance (105ish) which results in a V-shape for H2O molecule.
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Offline AWK

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Re:molecular shapes
« Reply #3 on: November 22, 2005, 02:41:53 AM »
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