Coulomb's force in atoms and effect on dipoles

In summary, the dipole moment of a polar molecule is due to the non-symmetric structure of the molecule, and the electron cloud "has trouble" being everywhere at once due to the lack of symmetry. The shielding of the dipole moment by other atoms makes the net force stronger than the individual forces, so the dipole moment doesn't collapse.
  • #1
SchrodingersMu
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Hi!
I've had this question for awhile. I asked my ochem professor and he didn't know how to answer it. My physics professor answered it but still left me with questions.

In physics, the force of two charged particles is shows by Coulombs eq: F= k* q1 * q2/ r^2.

My question is, why do dipoles even exist, if like charges repel? Take oxygen, for example. It has 8 protons, and needs 8 electrons to have a net charge of 0. As we see, when O bonds with H, it partly 'steals' the electrons from H.

Why wouldn't O, or any other molecule for that matter, just be satisfied with the e electrons that it gets from a bond? Why do electronegative atoms need to take EVEN MORE e? I feel that, by coulombs law, the extra e would be repelled by the other electrons.

My physics proff said that the electrons are attracted to O because of the difference in radii between the Oxygen atom, its electrons, and the electrons of the H.

That bring me to my same question again, though. Why would all of the electrons hang around on one side of oxygen? Things are more stable when charges are delocalized, so why wouldn't Oxygen delocalize the negative dipole it amasses?

I've been thinking about this for awhile, and my whole view on electronegativity has been shaken. Any help would be appreciated!
 
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  • #2
Polar molecules have a non-symmetric structure, so the electron cloud "has trouble" being everywhere at once due to the lack of symmetry ... hence water has a dipole moment.

Why doesn't it collapse? Because the forces holding the molecule together are stronger than the net force of the shielded dipole.

To work out the details from fundamental principles is difficult - something that may be a suitable PhD research topic in physical chemistry.
 

1. What is Coulomb's force?

Coulomb's force is an electrostatic force that describes the attraction or repulsion between two charged particles. It is named after French physicist Charles-Augustin de Coulomb.

2. How does Coulomb's force affect atoms?

Coulomb's force plays a crucial role in holding atoms together. The positively charged nucleus exerts an attractive Coulomb force on the negatively charged electrons, keeping them in orbit around the nucleus.

3. What is the effect of Coulomb's force on dipoles?

Coulomb's force can cause the alignment or orientation of electric dipoles, which are molecules that have a separation of positive and negative charges. This alignment is known as polarization and it is the basis for many important phenomena, such as the behavior of materials in electric fields.

4. How does distance affect Coulomb's force in atoms?

The strength of Coulomb's force decreases with distance. As the distance between two charged particles increases, the force between them decreases. This is known as the inverse-square law, meaning that the force is inversely proportional to the square of the distance between the particles.

5. Are there any other factors that affect Coulomb's force in atoms?

Yes, the magnitude of Coulomb's force also depends on the charges of the particles involved. The force between two particles with larger charges will be stronger than the force between two particles with smaller charges, even at the same distance. Additionally, the presence of other electrically charged particles in the vicinity can also affect the strength of Coulomb's force.

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