About the Orbital Dipole Moment

In summary, the convention in chemistry is to indicate the dipole moment with the arrows pointing from the central atom to the end of the hybridized orbital. The presence of a lone pair contributes to the dipole moment pointing towards the lone pair.
  • #1
S Aditya
2
0
I was going through the chapter Chemical Bonding in one of the books and found something about orbital dipole due to lone pairs.

In each diagram the orbital dipole due to lone pair was directed from the central atom to the end of the hybridized orbital (lone pair).

Why is that so?

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  • #2
Conventionally, in chemistry, the dipole moment is indicated as pointing from δ+ to δ-. This is in contrast with the convention in physics where the dipole moment points towards the positive charges.

The presence of the lone pair contributes to the δ-. In addition, the fact that there is a lone pair is an indication that the atom on which it resides is more electronegative, which explains the presence of the arrows pointing from H to N n the first figure. All this makes the dipole moment point towards the lone pair.
 
  • #3
DrClaude said:
Conventionally, in chemistry, the dipole moment is indicated as pointing from δ+ to δ-. This is in contrast with the convention in physics where the dipole moment points towards the positive charges.

The presence of the lone pair contributes to the δ-. In addition, the fact that there is a lone pair is an indication that the atom on which it resides is more electronegative, which explains the presence of the arrows pointing from H to N n the first figure. All this makes the dipole moment point towards the lone pair.

Sir, my argument is why is the dipole moment of the lone pair (and the lone pair alone) poining upwards (in this case) from the central atom (Nitrogen) to the extremity of the hybridized lone pair orbital?
 
  • #4
DrClaude said:
Conventionally, in chemistry, the dipole moment is indicated as pointing from δ+ to δ-. This is in contrast with the convention in physics where the dipole moment points towards the positive charges.
I never heard of such a convention. Rather, I think that the arrows denote the polarity of the bond, and not the dipole moment. But admittedly, for a non-bonding pair there is n't much sense in speaking of the polarity.
 
  • #6
Hm, maybe this is country specific?
 

Related to About the Orbital Dipole Moment

1. What is the orbital dipole moment?

The orbital dipole moment is a measure of the distribution of charge in an atom or molecule, specifically the distribution of the electrons in orbit around the nucleus. It is a vector quantity, meaning it has both magnitude and direction.

2. How is the orbital dipole moment calculated?

The orbital dipole moment is calculated by multiplying the charge on each electron by its distance from the nucleus and summing these values for all the electrons in the system. This calculation takes into account both the magnitude and direction of the charges, resulting in a vector quantity.

3. What is the significance of the orbital dipole moment?

The orbital dipole moment is significant because it provides information about the polarizability and reactivity of a molecule. It also plays a role in determining the strength of intermolecular forces, such as dipole-dipole interactions.

4. How does the orbital dipole moment differ from the molecular dipole moment?

The orbital dipole moment refers to the distribution of charge within an atom or molecule, while the molecular dipole moment refers to the overall separation of positive and negative charges in a molecule. The molecular dipole moment takes into account both the orbital dipole moments of each atom in the molecule and their arrangement in space.

5. Can the orbital dipole moment be measured experimentally?

Yes, the orbital dipole moment can be measured experimentally using techniques such as microwave spectroscopy or Raman spectroscopy. These methods can provide information about the molecular structure and the distribution of charge within a molecule.

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