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Lewis Structures before Forces

Posted: Tue Nov 13, 2018 10:33 pm
by Isabel Nakoud 4D
If a question provides a molecule and then asks about the expected or potential intermolecular forces of the molecule, should we draw the lewis structure and/or geometric structure?

I know that some molecules have a geometric shape that cancels out the dipoles, which changes the type of intermolecular forces expected of that molecule, but we can only predict this by going through the entire process of drawing the molecule.

How have you guys been approaching these problems? Anything helps.

Re: Lewis Structures before Forces

Posted: Tue Nov 13, 2018 11:24 pm
by jonathanjchang2E
Drawing out the lewis structure definitely helps in determining the shape of the molecule and I think it's best if you go that route until you're confident enough to determine the shape without drawing the lewis structure.

Re: Lewis Structures before Forces

Posted: Sat Nov 17, 2018 6:29 pm
by Sean Reyes 1J
Drawing the Lewis structure helps show the possible ways in which attraction can occur. For example, if you drew two water molecules side by side, you would notice the difference in electron density between the two molecules. This would lead you to draw the oxygen atom of one molecule being attracted to either hydrogen atom in the other molecule.
Additionally, noticing the electron density allows you to see the symmetry or lack of symmetry. For example, CH4 is pretty symmetric in electron density, which means there would be Van der Waals forces.
I hope this helps!

Re: Lewis Structures before Forces

Posted: Sat Nov 17, 2018 9:00 pm
by Catly Do 2E
I agree with the others who have responded. I feel that it is always best to start out with a Lewis structure and then go from there. You can determine the shape/structure and then observe how the intermolecular forces affect molecule interaction.