how do van der Wheels forces hold molecules together? please help i tried but i still cant understand it. thank you so much.
Van der Waals forces are a type of intermolecular force that hold molecules together. They arise due to fluctuations in electron distribution within molecules, leading to temporary asymmetry in charge distribution and the formation of temporary dipoles. This causes an attractive force between neighboring molecules.
To understand how van der Waals forces hold molecules together, it is helpful to understand the types of van der Waals forces:
1. London Dispersion Forces: These are the weakest van der Waals forces and exist between all molecules, regardless of their polarity. They arise due to the temporary imbalances in electron distribution. Even though individual molecules have no dipole moments, at any given moment, electrons may be unevenly distributed around a molecule, creating a temporary dipole. This temporary dipole can induce an opposite dipole in a neighboring molecule, resulting in an attractive force between them.
2. Dipole-Dipole Interactions: These occur between polar molecules, which have a permanent dipole moment due to an uneven distribution of charge. The positive end of one molecule is attracted to the negative end of a neighboring molecule, leading to an attractive force.
Now, let's discuss how van der Waals forces hold molecules together:
1. London Dispersion Forces: These forces are always present between all molecules, regardless of their polarity. It's important to note that even though the individual forces are weak, their cumulative effect can be significant, especially in larger molecules. London Dispersion Forces play a crucial role in holding nonpolar molecules together, such as hydrocarbons.
2. Dipole-Dipole Interactions: In polar molecules, the positive and negative ends of a molecule are attracted to opposite charges in neighboring molecules. This leads to an attractive force that helps hold polar molecules together. Dipole-dipole interactions are stronger than London dispersion forces and can significantly influence the physical properties and behavior of substances.
It's important to note that the strength of van der Waals forces depends on factors such as molecular size, shape, and the overall polarizability of the molecule.
In summary, van der Waals forces, including London Dispersion Forces and Dipole-Dipole Interactions, hold molecules together through temporary imbalances in charge distribution and the formation of attractive forces between neighboring molecules. These forces contribute to the overall stability and physical properties of substances.