Determining Dipoles

[Talia Leano 2H]

How do you determine if a molecule will have a dipole moment and therefore can have dipole-dipole interactions? For example why can CHCl3 have dipole-dipole interactions but not CCl4?

[Rich Luong 1D]

We determine that a molecule has dipole-dipole interactions when the electronegativity is unequally distributed throughout the molecule. In the case of CCl4, it only has London dispersion forces because all the chlorines surrounding the carbon have the same charge therefore distributing the electronegativity equally throughout the molecule. However, for CHCl3, when surrounding the carbon, H has an obvious unequal charge from the chlorines, indicating that the distribution of electronegativity would be unequal, indicating that the molecule also has dipole-dipole interactions. I hope this helps!

[Andre Fabian 1F]

Polar molecules contain polar bonds which contribute to the formation of dipoles. A good rule of thumb to keep in mind is that if a molecule has a symmetric structure (with the same atoms surrounding the core atom), then chances are it does not have a dipole moment, while polar molecules do have dipole moments.


Hope this helps!

[Alen Huang 2G]

It will have a dipole moment if the bond is polar and do not cancel out. CHCl3 is has polar bonds but is not symmetrical since H has lower electronegativity than Cl, Cl is going to have a slightly negative charge while H will have a slightly positive charge thus creating a dipole moment. CCl4 is symmetrical so its dipoles will cancel thus no dipole moment.

[Binyu You]

When a molecules' bonds are polar and do not cancel out(meaning it is non-polar), it will have a dipole moment. When a molecule is non-polar, it will only contain London dispersion force. CHCl3 in this case, has polar bonds and does not cancel out because Cl slightly negative and H is slightly positive, which means a dipole is created. Whereas CCl4's polar bonds cancel out, means it is non-polar, thus does not contain dipole moment.

[Ansh Patel 2I]

Hi! A molecule will have a dipole moment if the bond is polar and does not cancel out. Usually, symmetric structures like CH4 or CCL4 are not polar and only observe LDF.

[Emma_Barrall_3J]

CCl4 is non-polar and therefore does not have dipole-dipole interactions. Both molecules interacting must be polar in order for dipole-dipole interactions to occur.