Intermolecular Forces in Chemistry

These flashcards cover key concepts related to intermolecular forces, their types, effects on physical properties, and real-world applications as discussed in the lecture.

What are the three types of intermolecular forces?

Dispersion forces, dipole-dipole attractions, and hydrogen bonding.

What is the significance of kinetic energy in relation to intermolecular forces?

Kinetic energy helps to overcome intermolecular forces, influencing physical states of substances.

How are particles arranged in a solid?

Particles are tightly packed together in a regular pattern.

What occurs to gas particles when they are cooled?

They may condense into a liquid due to increased intermolecular attractions.

What is the process called when liquids turn into solids?

Freezing.

What type of force is London dispersion force?

A type of intermolecular force present in all condensed phases.

What does the strength of dispersion forces depend on?

The size and mass of the molecules.

How do intermolecular forces impact boiling points?

Stronger intermolecular forces lead to higher boiling points.

What is an example of a substance that can easily condense under pressure?

Butane (C4H10) when compressed in a lighter.

What is polarizability?

The ease with which a molecule's electron cloud can be distorted, affecting dispersion forces.

What are dipole-dipole attractions?

Attractive forces between the positive end of one polar molecule and the negative end of another.

What is hydrogen bonding?

A strong type of dipole-dipole attraction that occurs when H is bonded to F, O, or N.

Why does water have a higher boiling point than nitrosyl fluoride?

Water has stronger hydrogen bonding compared to nitrosyl fluoride's dispersion forces.

What happens to intermolecular forces when a substance transitions from gas to liquid?

Intermolecular forces increase as the distance between particles decreases.

What did Kellar Autumn discover about geckos?

Geckos stick to surfaces due to dispersion forces arising from interactions of tiny hairs.

What affects the boiling points of hydrocarbons?

The size of the molecules and the strength of dispersion forces.

How do the shapes of molecules influence their intermolecular forces?

More elongated shapes have larger contact areas, leading to stronger dispersion forces.

What is the relationship between molecular mass and boiling point for the halogens?

Boiling points increase with increasing molecular mass due to stronger dispersion forces.

What type of forces do nonpolar molecules primarily exhibit?

Dispersion forces.

What is a significant factor affecting hydrogen bonding strength?

The electronegativity difference between bonded atoms.

How do you rank the boiling points of similar compounds?

By considering the types and strength of intermolecular forces present.

What did the boiling points of ethanol and propane demonstrate?

Ethanol has higher boiling point due to strong hydrogen bonding compared to propane, which only has dispersion forces.

What are van der Waals forces?

The general term for all attractive forces between neutral atoms and molecules.

What does increasing pressure do to gas molecules?

It brings them closer, increasing intermolecular attractions and potentially forming liquids.

Why are hydrogen bonds important for water?

They contribute to water's unique properties, including high boiling point and surface tension.

How does a gecko switch between sticky and nonsticky?

By changing the angle of their spatulae relative to the surface.

Which intermolecular force is weaker, dipole-dipole or hydrogen bonds?

Dipole-dipole attractions are generally weaker than hydrogen bonds.

What can be used as indicators of the strength of intermolecular forces?

Boiling or freezing points, and enthalpies of vaporization or fusion.

Why are hydrogen bonds considered weak compared to covalent bonds?

They are approximately 5-10% as strong as covalent bonds.

What role does hydrogen bonding play in DNA structure?

It holds two strands of DNA together while allowing them to unzip for replication.

What effect do intermolecular forces have on solid, liquid, and gas states?

They determine the arrangement and motion of particles in each state.

Why do larger molecules have stronger dispersion forces?

They have greater electron clouds which can be more easily polarized.

What can occur to a liquid if its temperature is lowered sufficiently?

It can freeze into a solid if the kinetic energy is reduced below the strength of intermolecular forces.

Why do molecular shapes matter in determining boiling points?

Different shapes can increase or decrease the effective contact area between molecules.

What happens to the boiling point as intermolecular forces strengthen?

The boiling point increases.