London dispersion, Van der Waal, dipole dipole

[atlanta213]

London dispersion, Van der Waal, dipole dipole

I slightly remember these from my chemistry class in freshman. However, I never saw london dispersion in DAT review notes. Could you guys explain how these relate each other?

Thank you so much

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[osimsDDS]

London dispersion forces is the same thing as Van der Waals forces i believe...

H-bonding: you know what this is (FON) complexed with Hydrogen will give you hydrogen bonding, stronger than all the rest of the forces but covalent and ionic are way stronger.

Dispersion (dipole-dipole)- I believe this is the force when you have an induced dipole, unlike covalent when you are sharing electrons here you are not sharing electrons, its just the attraction/repulsion occuring with atoms of different dipoles, correct me if iam wrong but it occurs usually with linear molecules like alkanes and such...

 

[jdent]

Hey atlanta- look at an ochem book for question slike these- they explain it better!-

 

[klutzy1987]

OK there are 4 types of intermolecular forces

1) London/Dispersion/Van vaal - These are forces of attraction that exist between every molecule regardless of size or charge. The heavier an object the more dispersion forces it will have. They are cause by a partial temporary dipole on the molecule due to chance because the electrons are always moving. These foces of attraction are very weak and need very little energy to break.

2)Dipolo-Dipole - These are stronger than dispersion and exist only between 2 polar molecules. They are due to an attraction between the positive end (pole) of one and the negative end (pole) of the other molecule.

3)ion-dipole - exist between a polar uncharged molecule and a charged ion. The charge of the ion is attracted to the dipole of the polar molecule and a bond forms. This is slightly stronger than a dipole-dipole.

4) H-bonding - exist between any molecules that have a hydrogen bonded to either a O,N,F. The negative N,O,F bond to the positively charged H. These bonds are the strongest intermolecular bonds. They are so strong, because the N,O,F is very electronegative and therfore creates a very strong dipole on the h and N,O,F. This strong dipole is what allows for H-bonding and H-bonding is one of the main components of all organic molecules.

I hope this helps any questions just ask.

 

[joonkimdds]

However, I never saw london dispersion in DAT review notes.

becuz it's in London....😛

 

[DCRedskinsRule]

OK there are 4 types of intermolecular forces

1) London/Dispersion/Van vaal - These are forces of attraction that exist between every molecule regardless of size or charge. The heavier an object the more dispersion forces it will have. They are cause by a partial temporary dipole on the molecule due to chance because the electrons are always moving. These foces of attraction are very weak and need very little energy to break.

2)Dipolo-Dipole - These are stronger than dispersion and exist only between 2 polar molecules. They are due to an attraction between the positive end (pole) of one and the negative end (pole) of the other molecule.

3)ion-dipole - exist between a polar uncharged molecule and a charged ion. The charge of the ion is attracted to the dipole of the polar molecule and a bond forms. This is slightly stronger than a dipole-dipole.

4) H-bonding - exist between any molecules that have a hydrogen bonded to either a O,N,F. The negative N,O,F bond to the positively charged H. These bonds are the strongest intermolecular bonds. They are so strong, because the N,O,F is very electronegative and therfore creates a very strong dipole on the h and N,O,F. This strong dipole is what allows for H-bonding and H-bonding is one of the main components of all organic molecules.

I hope this helps any questions just ask.

Just a few mods...

Ion-dipole forces are STRONGER than hydrogen bonds and are actually the strongest of the intermolecular forces.

Also, be careful with hydrogen bonds b/c they're not ACTUALLY bound to the N,O, or F. They are just attracted to them b/c of there extreme electronegativities. BONDS are INTRAmolecular interactions so the term "hydrogen bond" is actually a misnomer. Also, definitely not ALL organic molecules demonstrate hydrogen bonding.

 

[klutzy1987]

Just a few mods...

Ion-dipole forces are STRONGER than hydrogen bonds and are actually the strongest of the intermolecular forces.

Also, be careful with hydrogen bonds b/c they're not ACTUALLY bound to the N,O, or F. They are just attracted to them b/c of there extreme electronegativities. BONDS are INTRAmolecular interactions so the term "hydrogen bond" is actually a misnomer. Also, definitely not ALL organic molecules demonstrate hydrogen bonding.

Ion dipole are not necessarily stronger than Hydrogen Bonding, it depends on how strong the dipole is. A molecule that is barely polar is not going to have a very strong ion dipole bond. H bonding has the potential to be much stronger than ion dipole, and i guess vice versa.

 

[Neuro178]

Hey atlanta- look at an ochem book for question slike these- they explain it better!-

Uhh yeah, check a textbook - preferably a gen chem book - about intermolecular forces. Some of these responses are conflicting and not quite what I learned. Take them with a grain of salt!

P.S. Understanding intermolecular forces are VITAL for many types of gen chem & ochem questions. Think boiling points, solubility, etc...