Intermolecular forces Flashcards
Proof for LDFs?
- Exist between all molecules.
- Proof is that all molecular elements and monotomic elements freeze when cooled, so there must be some attractive forces existing between them.
How are LDFs made?
These forces are much weaker than all other types of bonding. They are formed as a result of electrostatic attraction between temporary dipoles and induced dipoles (one temporary dipole making another temporary dipole) caused by movement of electrons in atoms and molecules.
What effects the stregnth of LDFs?
The strength of London dispersion forces depends on the size of the molecule or atom.
Larger atoms and molecules have more electrons. This leads to larger dipoles being established.
What are permanent dipole - permanent dipole interactions?
Permanent dipole-permanent dipole interactions are additional electrostatic forces of attraction between polar molecules. Permanent dipole-permanent dipole interactions are stronger than London dispersion
forces for molecules with similar numbers of electrons.
What is hydrogen bonding?
Hydrogen bonding is the strongest type of intermolecular bond.
It is a specific type of permanent dipole to permanent dipole attraction that occurs when a hydrogen atom is covalently bonded to a highly electronegative element such as nitrogen, oxygen or fluorine.
Weaker that covalent bonds
Rank the stregnth of intermolecular bonds.
Covalent bonds > Hydrogen bonds > Permanent dipole interactions > London dispersion forces.
What happens to water when it freezes?
The density of ice is less than water. This is due to the water expanding as it is frozen because of the hydrogen forming an open type lattice.
