Jan 4, 2012
1,479
4
Status
Pre-Medical
If a questions ask about forces between molecules, it's talking about INTERmolecular forces-(How will I remember this? Maybe INTERmolecular forces are to molecules and compounds as INTERstates are to different states...)

INTERmolecular forces are-- strongest to weakest
1. covalent bonds
2. hydrogen bonding
the next two are van der Waals
3. dipole dipole
4. London dispersion forces

Distinguishing b/w dipole & covalent:
I suspect, from AAMC7, it's difficult to predict whether a compound exhibits covalent or dipole-dipole bonds (or both) just by looking at it. But given that covalent bonds are really strong, a really low boiling point likely means that they are not around. :thumbup: :thumbdown: ?

London dispersion forces:
Are they always around?

INTRAmolecular bonds
Ionic, metallic & covalent

2 questions:

Is what I have written from strongest to weakest?
And are covalent bonds then intramolecular and intermolecular forces?
 

SH3

Oct 4, 2011
226
5
Nashville, TN
Status
Medical Student
If a questions ask about forces between molecules, it's talking about INTERmolecular forces-(How will I remember this? Maybe INTERmolecular forces are to molecules and compounds as INTERstates are to different states...)

INTERmolecular forces are-- strongest to weakest
1. covalent bonds
2. hydrogen bonding
the next two are van der Waals
3. dipole dipole
4. London dispersion forces

Distinguishing b/w dipole & covalent:
I suspect, from AAMC7, it's difficult to predict whether a compound exhibits covalent or dipole-dipole bonds (or both) just by looking at it. But given that covalent bonds are really strong, a really low boiling point likely means that they are not around. :thumbup: :thumbdown: ?

London dispersion forces:
Are they always around?

INTRAmolecular bonds
Ionic, metallic & covalent

2 questions:

Is what I have written from strongest to weakest?
And are covalent bonds then intramolecular and intermolecular forces?

Intra is within, Inter is b/w - just memorize it.
Covalent bonds are considered an intramolecular force because they are exhibited within individual molecules and compounds.
The other forces you've listed (Hydrogen bonds, Dipole-Dipole and Van der Waals) are intermolecular forces because they only act between molecules and compounds.

London Dispersion forces always exist as they are due to the "random" shuffling of electrons in orbitals that cause temporary weak dipoles in atoms and therefore molecules.

Strongest to weakest is: Hydrogen bonding, Dipole-Dipole, Van der Waals.
Covalent, as I've said previous are intramolecular forces.
 
Last edited:

pm1

Mar 21, 2012
323
8
Status
Pre-Medical
I think SH3 meant to say INTERmolecular forces when referring to H bonds, Dipole-Dipole, and Van der Waals.

This might help you (it helps me): if you think of the word INTERact def: Act in such a way as to have an effect on another , you can't interact with yourself.
 

SH3

Oct 4, 2011
226
5
Nashville, TN
Status
Medical Student
I think SH3 meant to say INTERmolecular forces when referring to H bonds, Dipole-Dipole, and Van der Waals.

This might help you (it helps me): if you think of the word INTERact def: Act in such a way as to have an effect on another , you can't interact with yourself.
Thanks, i edited the original post
 
May 29, 2011
444
1
Status
Pre-Medical
All non ionic molecules have covalent bonds, those are not intermolecular forces. Only h-bonding, dipole dipole, and dispersion forces are considered intermolecular forces.

Ionic compounds have much higher boiling and melting points than covalent compounds.