Are repulsive Van der Waals forces as common as attractive ones?

In summary, the temporary dipoles formed by vander vaal's forces can cause attraction between neighboring molecules when their oppositely charged ends line up. However, this effect does not occur as frequently or strongly when the similarly charged ends point together and cause repulsion. This is due to the dipoles inducing each other in an attractive way, similar to a magnet attracting a nonmagnetic piece of iron."
  • #1
24forChromium
155
7
I may be as wrong as an alchemist, but according to what I know, many substance stay together because of vander vaal's forces (I forgot how it's spelt) which is essentially the temporary dipoles that form around molecules, some times, the dipoles line up such that two neighbouring molecules have oppositely charged ends pointing at one another, causing attraction. My question is, why don't the same effect be just as strong and frequent in the cases where the similarly charged dipole ends point together and cause repulsion, pushing the substance apart on the molecular scale?
 
Physics news on Phys.org
  • #2
The dipoles induce each other - and this is always in an attractive way. It's similar to a magnet attracting a nonmagnetic piece of iron. The field leads to the correct orientation for attraction.
 
  • Like
Likes 24forChromium

1. What are Van der Waals forces?

Van der Waals forces are weak intermolecular forces that exist between atoms and molecules. They are caused by temporary dipoles that are created due to the uneven distribution of electrons within atoms and molecules.

2. How do Van der Waals forces affect the physical properties of substances?

Van der Waals forces play a significant role in determining the physical properties of substances, such as melting and boiling points, viscosity, and surface tension. These forces also contribute to the cohesive forces between molecules, which affect the strength of solids and liquids.

3. What is the difference between London dispersion forces and dipole-dipole interactions?

London dispersion forces are a type of Van der Waals force that exists between all atoms and molecules, regardless of their polarity. These forces are caused by temporary dipoles that are induced by the movement of electrons. On the other hand, dipole-dipole interactions occur between polar molecules and are caused by the attraction between the positive and negative ends of the molecules.

4. How do Van der Waals forces contribute to the structure of biological molecules?

Van der Waals forces play a crucial role in the structure of biological molecules, such as proteins and DNA. These forces help to stabilize the shape of these molecules, which is essential for their proper function. For example, hydrogen bonds, a type of Van der Waals force, contribute to the double helix structure of DNA.

5. Can Van der Waals forces be manipulated or controlled?

Yes, Van der Waals forces can be manipulated or controlled by changing the distance between molecules or altering their polarity. For example, the addition of polar molecules can increase the strength of Van der Waals forces between nonpolar molecules, leading to stronger intermolecular interactions. These forces can also be weakened by increasing the distance between molecules, such as through the addition of a solvent.

Similar threads

I Wall material effect on Van der Waals gas?
    • Classical Physics
Replies
23
Views
1K
I Van der Waals Equation: How Surface is Considered
    • Classical Physics
2
Replies
39
Views
2K
I How does a magnetic field affect the aggregation of nonpolar molecules in water?
    • Other Physics Topics
Replies
1
Views
909
I What is the origin of Van der Waals force?
    • Atomic and Condensed Matter
Replies
24
Views
7K
Effects of Intermolecular Forces?
    • Other Physics Topics
Replies
7
Views
5K
Van der Waals' Forces and Hydrogen Bonding
    • Chemistry
Replies
2
Views
2K
Van der Waals forces between woven carbon nanotubes
    • Materials and Chemical Engineering
Replies
6
Views
2K
I Attractive van der Waals force between similar atoms/molecules
    • Quantum Physics
Replies
10
Views
1K
B What's the energy source for the Van der Waals' forces?
    • Atomic and Condensed Matter
Replies
4
Views
1K
Compressibility factor and van der Waals equation for temp
    • Classical Physics
Replies
3
Views
4K

Hot Threads

Recent Insights

Back
Top