Hello Everyone! Thank you for stopping by my website to learn about Intermolecular Forces.
Why you should understand Intermolecular Forces: Intermolecular forces are responsible for the interactions or lack of interactions between different substances. For example, hydrogen bonding is the reason your DNA is able to stay together for an extended period of time. And without intermolecular forces things like surface tension and the boiling points of different substances would all be the same. In short, Intermolecular forces are important. I'll get off my soapbox now.
Important Concepts:
- Intermolecular forces versus intramolecular forces
- Types of intermolecular forces including hydrogen bonding, ion-dipole, dipole-dipole, and Van der Waals forces (also known as London dispersion forces).
- Comparing intermolecular forces to ionic and covalent bonds (strength wise)
Intermolecular forces versus intramolecular forces
Intermolecular forces are interactions that exist between molecules. Intramolecular forces are the bonds that hold molecules together. Intermolecular forces include hydrogen bonding, ion-dipole interactions, dipole-dipole interactions, and London dispersion forces.
Intramolecular forces are stronger than intermolecular forces because they hold actual atoms together. Intramolecular forces are technically bonds, which are a type of force that holds atoms together. Bonds are interactions between the valence electrons of atoms. For this reason, bonds are stronger than intermolecular forces. The two main types of intramolecular forces are covalent bonds and ionic bonds. Covalent bonds come in two flavors, polar covalent bonds, and nonpolar covalent bonds. The differences between these two types of covalent bonds are based on electronegativity.
Intermolecular forces are interactions between molecules that are caused by differences in electronegativity and partial charges.
Types of intermolecular forces
There are four types of intermolecular forces: London dispersion forces, hydrogen bonding, ion-dipole interactions, and dipole-dipole interactions.
London dispersion forces are the weakest of the intermolecular forces. They exist between all molecules in solution, regardless of if they have partial charges or dipole moments.
Dipole-dipole interactions occur between covalently bonded molecules. These molecules either have partial charges due to differences in electronegativity or experience a temporary dipole moment.
Ion-dipole interactions take place between one molecule that has a totally positive or negative charge and another molecule that only has a partial positive or negative charge. One molecule is typically an ionically bound substance while the other is a polar covalent bond.
Hydrogen Bonding is the strongest of the intermolecular forces. Hydrogen bonding occurs only between an H-F, H-I, H-O, and another Hydrogen. Meaning one molecule has a hydrogen bound to one of the three molecules. While the other molecule has a hydrogen.
Comparing intermolecular forces to ionic and covalent bonds
Though hydrogen bonding is the strongest of the intermolecular forces, it is not stronger than a covalent or ionic bond. Intermolecular forces are always weaker than intramolecular forces. Covalent bonding is the strongest of all the forces.
Summary
- Intermolecular forces are interactions that exist between molecules. Intramolecular forces are the bonds that hold molecules together.
There are four types of intermolecular forces: London dispersion forces, hydrogen bonding, ion-dipole interactions, and dipole-dipole interactions.
- Intermolecular forces are always weaker than intramolecular forces.
I hope you've found this post on intermolecular forces helpful. If you have any questions feel free to comment on this post, email me, or comment on the video I've linked below.
- Saren
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