Determining Intermolecular Forces

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Jasmine Reddy DIS 1E
Posts: 34
Joined: Fri Sep 28, 2018 12:17 am

Determining Intermolecular Forces

Postby Jasmine Reddy DIS 1E » Tue Nov 13, 2018 7:32 pm

Is there a way to determine which intermolecular forces will occur between certain molecules solely by looking at the chemical equation (without drawing the lewis structure)?
For example, would you be able to tell which intermolecular forces would occur between H2SeO4 molecules without drawing the lewis structure?

Ray Guo 4C
Posts: 90
Joined: Fri Sep 28, 2018 12:15 am

Re: Determining Intermolecular Forces

Postby Ray Guo 4C » Tue Nov 13, 2018 8:14 pm

Try to determine whether the molecule is ionic, polar covalent, or non-polar covalent. Ionic compounds have ion-ion interaction. Polar molecules have polar-polar or hydrogen bonding. And, I think, all three have London dispersion forces.

Andre_Galenchik_2L
Posts: 69
Joined: Fri Sep 28, 2018 12:23 am

Re: Determining Intermolecular Forces

Postby Andre_Galenchik_2L » Tue Nov 13, 2018 10:01 pm

You can also look where the particular element is on the periodic table. Metals and nonmetals tend to form ionic bonds and two nonmetals tend to form covalent bonds.

jonathanjchang2E
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Joined: Fri Sep 28, 2018 12:26 am

Re: Determining Intermolecular Forces

Postby jonathanjchang2E » Tue Nov 13, 2018 11:18 pm

You can determine the intermolecular forces on most molecules just by its chemical equation. For example, if the molecule has hydrogen and N,O, or F it has hydrogen bonding. If the molecule is polar like CHCL3 then it will have dipole dipole interaction and all molecules are able to have London interactions due to the instantaneous dipole moment.

Chem_Mod
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Re: Determining Intermolecular Forces

Postby Chem_Mod » Wed Nov 14, 2018 9:40 am

The best way to determine what kind of intermolecular bonding the molecules will undergo is by looking at the Lewis structure. Just because there is H and N,O,F on the molecule does not mean they can undergo hydrogen bonding, since the requirement is the H is bonded specifically to N, O, or F. Additionally, just because the molecule has electronegative elements does not mean the molecule overall will be polar. If the dipoles of each bond cancel out, then the molecule is nonpolar and experiences mostly van der Waals interactions. Something to keep in mind as you look for patterns in the practice problems!

Henry Dudley 1G
Posts: 61
Joined: Fri Sep 28, 2018 12:16 am

Re: Determining Intermolecular Forces

Postby Henry Dudley 1G » Thu Nov 15, 2018 11:14 pm

In order to determine what kind of molecular forces you are dealing with, you need to know if the atom is polar or not. How do you determine wether an atom is polar or non polar?


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