Types of intramolecular forces

(Polar molecules, Non-polar molecules, etc.)

Moderators: Chem_Mod, Chem_Admin

Shreya Tamatam 3B
Posts: 30
Joined: Fri Sep 28, 2018 12:25 am

Types of intramolecular forces

Postby Shreya Tamatam 3B » Sat Dec 01, 2018 12:28 pm

How do you determine what type of forces are present in a molecule? eg. How do you determine if a force is a dipole-dipole interaction versus a Van Der Waals force?

Ibrahim Malik 1H
Posts: 65
Joined: Fri Sep 28, 2018 12:27 am
Been upvoted: 1 time

Re: Types of intramolecular forces

Postby Ibrahim Malik 1H » Sat Dec 01, 2018 12:41 pm

You can determine the type of forces present in a molecule by looking at the structure of the molecule and the elements bonded to each other. For example, if a Hydrogen is bonded to either a Fluorine, Oxygen, or Nitrogen, hydrogen bonding is present. A dipole-dipole interaction is a type of Van Der Waals force, the three types being London dispersion forces, dipole-dipole interactions, and hydrogen bonding.

Alli Hinmon 3E
Posts: 30
Joined: Wed Nov 08, 2017 3:00 am

Re: Types of intramolecular forces

Postby Alli Hinmon 3E » Sat Dec 01, 2018 7:06 pm

The way I mentally do these types of problems is process of elimination. First I see if it has AX4, and all the Xs are the same element. Right away I know its non polar. All non polar molecules are induced dipole-dipole.
If this is not the case, I always start by looking at the Lewis structure and seeing, does it have any bonds with H bonding to N, O, or F? If it does it has H-Bonding. Whenever there is H-Bonding there is usually Dipole-Dipole, as long as the H-bonding doesn't cancel itself out by bonding to another H on the opposite side.

SydBenedict2H
Posts: 60
Joined: Wed Nov 08, 2017 3:00 am

Re: Types of intramolecular forces

Postby SydBenedict2H » Sat Dec 01, 2018 7:55 pm

What if the molecule is polar and doesn't have hydrogen bonding?

505095793
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am

Re: Types of intramolecular forces

Postby 505095793 » Sun Dec 02, 2018 4:28 pm

To determine the forces present in the molecule it is easiest to first draw out the Lewis structure. First look for ionic forces, look for an interaction between a cation and an anion (Such as Na+ and Cl-). Then, you can look for hydrogen bonding. Hydrogen bonding occurs when a hydrogen is bonded to nitrogen, oxygen, or fluorine. Next, look for dipole-dipole interactions. These dipole-dipole forces occur when there is a difference in electronegativity in the molecule. In other words, there are points that are more electronegative than other points of the molecule. Finally, look for Dispersion forces (also called London forces). Dispersion forces occur when there is an instantaneous attraction between dipoles in a molecule. Keep in mind that all molecules regardless of whether they are polar or not have dispersion forces present.


Return to “Determining Molecular Shape (VSEPR)”

Who is online

Users browsing this forum: No registered users and 1 guest