Intermolecular Forces

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Sunia Akaveka 4I
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Intermolecular Forces

Postby Sunia Akaveka 4I » Wed Nov 20, 2019 10:56 pm

Hi, I'm still a bit confused about how you know which intermolecular forces are involved given just the chemical formula. Can someone explain this to me? (For reference, I'm talking in regards to problems like 3F.1 and 3F.2)

Marty Hockey
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Re: Intermolecular Forces

Postby Marty Hockey » Wed Nov 20, 2019 11:37 pm

You can determine whether or not a molecule is capable of hydrogen bonds based on if it has an OH, HF, or NF bond or not as is the case for 3f1a, it is London forces for b) because it is nonpolar so it can't be a dipole, and it can have a dipole-dipole moment for d) because it is polar. Hope this helps!

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Re: Intermolecular Forces

Postby Veronica_Lubera_2A » Thu Nov 21, 2019 9:15 am

Also every molecule will have London dispersion (induced dipole-induced dipole) forces present.

Justin Sarquiz 2F
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Re: Intermolecular Forces

Postby Justin Sarquiz 2F » Thu Nov 21, 2019 9:25 am

Dipole dipole is present if the molecule is polar. In order to have Hydrogen bonding, a hydrogen must bond with an electronegative oxygen, nitrogen, or fluorine, and these three elements must have an extra lone pair in order to bond.

Ariana Iranmahboub1G
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Re: Intermolecular Forces

Postby Ariana Iranmahboub1G » Thu Nov 21, 2019 9:47 am

Yes a hydrogen bond forms between hydrogen and N, O, and F. Dipole-dipole interactions form when two polar atoms/molecules interact. Ion-Dipole form when a ion interacts with a polar molecule. Ion-ion interactions form when two ions interact with each other. Dispersion (also called London Forces, induced dipole-induced-dipole, Van der Waals) occurs with all molecule interactions including nonpolar molecules.

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Re: Intermolecular Forces

Postby AGulati_4A » Thu Nov 21, 2019 10:18 am

All molecules have the LDF force. A molecule has a dipole-dipole interaction if it has a large difference in electronegativity -- which gives partial charges to each side of the molecule. Additionally, if the molecules have dipoles that do not cancel -- then they are a polar molecule. Further, if a molecule has an F, O, or N atom with a lone pair and is bonded to a Hydrogen molecule -- it has the potential to create a hydrogen bond.

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Re: Intermolecular Forces

Postby alexfwang3g » Thu Nov 21, 2019 10:19 am

Draw it out and identify dipole or lack of dipole. Consider if there is F, O, or N for hydrogen bonding. Every molecule has LDF.

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Re: Intermolecular Forces

Postby selatran1h » Thu Nov 21, 2019 11:13 pm

To determine intermolecular forces, you have to look at what elements are involved, how they are bonded, and their polarity. If there is an H in the compound, it is likely there is hydrogen bonding. If the atoms are non polar, it is likely the forces are London dispersion.

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