Molecular interactions Flashcards
Deck focused on learning the different types of intermolecular interactions according to the type of molecule.
What are intermolecular interactions?
They are forces that act between molecules, influencing their physical properties.
Unlike chemical bonds, they do not involve the sharing or transfer of electrons. In addition, there are different types of intermolecular interactions depending of the molecular structure. The main types are dipolar interactions, London dispersion forces, and hydrogen bondings.
What are the main types of intermolecular interactions?
The main types are dipolar interactions, London dispersion forces, and hydrogen bondings.
Dipolar interactions include permanent dipole and dipole-induced interactions, which are characteristic of polar molecules (e.g., suggar). London dispersion forces are weak, non-permanent dipole interactions and are characteristic of non-polar molecules (e.g., hydrocarbons). Hydrogen bonding is characteristic of molecules with hydrogen atoms bonded to high electronegative atoms, such as oxygen, nitrogen and fluor (e.g., water).
What is a hydrogen bond?
It is a strong interaction between a hydrogen atom and an electronegative atom (such as oxygen or nitrogen) in another molecule.
This type of bonding is key in water and in the structures of biomolecules such as DNA.
How do intermolecular interactions affect the properties of a substance?
They determine boiling point, melting point, solubility and physical state.
The stronger the intermolecular interactions, the higher the boiling and melting points. Hydrogen bonds can be the strongest interactions, followed by dipole interactions, and finally, London dispersion forces, which are the weakest. These differences in strength also influence solubility: molecules with hydrogen bonds tend to be more soluble in water than those with only dispersion forces.
What are London dispersion forces?
They are weak interactions between nonpolar molecules due to temporal fluctuations in electron distribution.
These forces arise from the formation of instantaneous dipoles in molecules, which induce dipoles in nearby molecules. Although they are the weakest interactions, they become significant in large molecules and affect the boiling point of noble gases and nonpolar compounds.
