Can You Help Me Understand Molecular Dipole Moments?

[babbagee]

Molecular dipole moment?

What is a Molecular Dipole moment. My book explains it but i still don't get it. And here is a problem that ask me about it.

Which molecule in each pair has the greater dipole moment
a. SO₂ or SO₃
b. ICl or IF
c. SiF₄ or SF₄
d. H₂O or H₂S

Give the reason for your choice.

You only have to do one or two. After that ill get the point.

Thanks

 

[repugno]

A dipole moment is created when there is a difference in electronegativity between the bonded atoms. Thus, electrons from one atom is attracted closer to the other causing one atom to become \delta+ and the other \delta-. Hope this helps.

 

[himanshu121]

u should know the electronegative value and the shape/structure of the compound

for eg in SO₃ u have planar triangular structure with angle 120⁰ so the dipoles which are vector quantity gets canceled and u have dipole moment=0

The direction of dipole moment is from + to - direction

 

[nautica]

Intermolecular Force.

These are in order of strongest weakest, and the H bonding is only 5% as stong as an acutal bond.

1. Hydrogen Bonding (water molecules)
2. Dipole Moment (polar molecules)
3. London Forces (extremely week but interesting)

Nautica

 

[Dr.Brain]

Man..what has Hydrogen Bonding to do with dipole?

See Dipole moment is donated by ::: u

And u can claculate net ""U"" of a compound by taking resultant of different u's of different bonds...

Like in SO3...calculate net "u" of SO SO SO ...as three O are bonded to single S... use parallelogram law vector method if u know the angle between the bonds...by knowing type of hybridization.

 

[nautica]

Originally posted by Dr.Brain
Man..what has Hydrogen Bonding to do with dipole?

Has everything to do with it. They are both intermolecular forces which dictate melting points, boiling points, ect... I just figured you would like to know what they would be compared to, but I guess I was wrong.

Nautica

 

[JPJ]

Hi folk
May be anybody knows where I can found information (research articles) about transition dipole moments in quinone like molecules, especially in benzoquinone, phylloquinone , menaquinone. Someone told that these study already done, but I found nothing in search engines.

JPJ

 

[Monique]

Hi JPJ, did you try: http://www.ncbi.nlm.nih.gov/PubMed it is where all the published peer-reviewed articles get collected.. usually they are biology oriented so it might not be found there though.. :S

Um.. otherwise I wouldn't know from the top of my head..

 

[iluvsr20s]

What is a Molecular Dipole moment. My book explains it but i still don't get it. And here is a problem that ask me about it.

Which molecule in each pair has the greater dipole moment
a. SO₂ or SO₃
b. ICl or IF
c. SiF₄ or SF₄
d. H₂O or H₂S

Give the reason for your choice.

You only have to do one or two. After that ill get the point.

Thanks

If you have to draw out the Lewis structures for each of them, it will help you see it better at first, and then its all about the electronegativity.

Sorry this is a question of pure laziness but is SO₂ linear bent, i just thought that that was the only way the problem would work since the SO₃ has a zero dipole moment.

 

[Beren]

Yeah, SO2 is linear bent, because of the lone pair.

 

[2Pac]

1. Hydrogen Bonding (water molecules)
2. Dipole Moment (polar molecules)
3. London Forces (extremely week but interesting)

Hydrogen bonding occurs in any molecule that has Hydrogen bonded with F, O, Cl and S too i belive.

A hydrogen bond can be thought of as a "super dipole" as it is just that; a dipole high strength dipole bond

In order to answer your question you must draw the lewis structures for all the atoms.

a) SO2 (it is non polar so contains dipole. the SO3 is polar)

b) IF (the attraction between I and F is stronger than I and Cl)

c) SF4 (again by drawing the lewis structures you can determine that SF4 is polar and SiF4 is not)

d) H20 (stronger dipole moment)