Intermolecular Forces Lecture Notes

A comprehensive set of flashcards covering key concepts and details on intermolecular forces from the lecture notes.

How do intermolecular forces affect boiling points?

They help determine physical properties like boiling and melting points.

What are intramolecular forces?

Strong bonds within a molecule, such as covalent or ionic bonds.

What does bonding and intermolecular forces compare in terms of strength?

Intermolecular forces are generally much weaker than bonding forces.

What is the purpose of dispersion forces (aka London forces)?

They occur due to fluctuations in electron distributions in atoms.

How does molar mass affect dispersion forces?

Dispersion forces increase with increasing molar mass.

What defines the strength of dispersion force?

The ease at which electrons can move or polarize.

Do nonpolar molecules have dispersion forces?

Yes, nonpolar molecules only have dispersion forces.

What is a dipole-dipole force?

Attractive force between polar molecules with permanent dipoles.

How does molecular shape influence boiling points?

Longer molecules have a larger area for interaction, increasing dispersion strength.

What is hydrogen bonding?

A strong dipole-dipole force involving hydrogen bonded to electronegative atoms.

What types of elements typically form hydrogen bonds?

Commonly with oxygen, nitrogen, or fluorine.

What are ion-dipole forces?

Forces that occur when an ionic compound is mixed with a polar compound.

What is the key factor for the solubility of ionic compounds in water?

The strength of ion-dipole attraction.

Which intermolecular force is the strongest in general?

Hydrogen bonding

What happens when ion-dipole attractions are strong enough?

They can overcome the forces holding the ionic compound together, leading to dissolution.

What is the boiling point of helium?

4.2 Kelvin

What is a common characteristic of hydrogen-bonding substances?

They have higher melting and boiling points compared to those that do not form hydrogen bonds.

Why are dispersion forces always present?

They are found in all molecules and atoms.

How does molecular size influence boiling point?

Boiling point typically increases with increasing molar mass.

What is the relationship between dipole moment and boiling point?

Boiling point increases with dipole moment.

What defines the bond order in molecular orbital theory?

A bond order above zero is stable; a bond order of zero is unstable.

What is the effect of increasing molar mass on dispersion forces?

Stronger dispersion forces lead to increasing boiling points.

What is one example of a molecule that exhibits hydrogen bonding?

Ethanol (CH3CH2OH)

Do all molecules that are polar have dispersion forces?

Yes, all polar molecules also exhibit dispersion forces.

What is the role of electronegative atoms in hydrogen bonding?

They strongly attract electron clouds from neighboring molecules.

How do intermolecular forces determine the state of a substance?

They determine whether the substance exists as a solid, liquid, or gas at a given temperature.

What type of interaction occurs in ion-dipole forces?

The attraction between the positive end of a polar molecule and negative ions.

How do dispersion forces operate on a molecular level?

They arise from instantaneous dipoles inducing similar dipoles in neighboring molecules.

Which intermolecular force can become very strong for high molar mass molecules?

Dispersion forces can become as strong as other types of intermolecular forces.