Honors Chemistry Unit 11 - Intermolecular Forces

Forces between atoms in a compound are ______________ ______.

intramolecular forces

Forces that act between molecules are ______________ ______.

intermolecular forces

_____ _________ have very strong bonds (attractive forces) so they have high melting points and boiling points.

ionic compounds

________ _________ have lower melting and boiling points because covalent bonds are not as strong as ionic bonds.

covalent compounds

Generally, intermolecular forces are much ______ than intramolecular forces.

weaker

We can use _________________ to predict what kind of bond will form.

electronegativity

_____ _________ are like a battery, they have a positive and a negative end (like two poles of a planet or a magnet); the ends are opposite of each other.

polar molecules

A ______-______ _____ happens between the partial charges of polar molecules.

dipole-dipole force

The ____ polar the molecules are, the stronger the dipole-dipole forces between them, and thus, the higher the boiling point.

more

________ _____ involve the attraction between polar molecules that contain hydrogen and molecules that have N-H, O-H, or F-H bonds.

hydrogen bonds

________ _____ are very strong because hydrogen atoms are small and very polar (a large difference in electronegativity between atoms).

hydrogen bonds

Water has unique properties because of all the strong ________ _____.

hydrogen bonds

______ __________ ______ are nonpolar molecules, like F₂, which can become momentarily polar which results in a force of attraction between the molecules.

London dispersion forces

In ______ __________ ______, electrons are moving around in atoms, so there may be times when the electron distribution is not symmetrical).

London dispersion forces

___-______ ______ are the interaction or attraction between an ion and a polar molecule.

ion-dipole forces

An example of ___-______ _____ includes any ionic compound that dissociates into ions when dissolved in water (like NaCl in water or AgNO₃ in water).

ion-dipole forces

In _____, because the particles are so far apart, the attractive forces between them do not have a great effect.

gases

_____ are fluids and can flow easily because the particles move freely.

gases

In ______, particles can only vibrate in place and do not break away from their fixed positions.

solids

In ______, the particles are held very close together by attractive forces.

solids

In _______, liquid particles are held together by attractive forces so that they still touch each other but the particles have enough energy to move past each other easily (that's why they flow).

liquids

When a solid turns into a liquid.

fusion (melting)

When a liquid turns into a solid.

freezing

When a liquid turns into a gas.

vaporization

When a gas turns into a liquid.

condensation

When a solid turns into a gas.

sublimation

When a gas turns into a solid.

deposition

_____ ________ relates to the tendency of atoms or molecules to escape from liquids or solids; a measure of how easily a substance can enter the gas phase.

vapor pressure

Temperature and intermolecular forces are two factors that affect _____ ________.

vapor pressure

At room temperature, the stronger the intermolecular force equals the _____ vapor pressure.

lower

At room temperature, the weaker the intermolecular force equals the ______ vapor pressure.

higher

A substance with a high vapor pressure at normal temperatures is often referred to as ________.

volatile

_______ _____ is the temperature at which the vapor pressure of a liquid equals the external pressure.

boiling point

When atmospheric pressure decreases, vapor pressure _________ (less pressure pushing down means it can escape to the gas phase easier) = lower boiling point!

increases

When atmospheric pressure increases, vapor pressure _________ (more pressure pushing down so it can't escape to gas phase as easily) = higher boiling point!

decreases

_____ ____ __ ______ is the energy required to change 1 mole of ice into 1 mole of water at 0°C.

molar heat of fusion

_____ ____ __ ____________ is the amount of energy required to change 1 mole of water from the liquid state to the gaseous state.

molar heat of vaporization

_______ _______ is the tendency of liquids to decrease their surface area to the smallest size possible. Liquids tend to form spherical shapes because a sphere has the smallest surface area for a given volume.

surface tension