Question 1

What are the four intermolecular forces?

Accepted Answer

London Dispersion Forces

Dipole-Dipole

Hydrogen Bonding

Ion-Dipole

Question 2

What are London dispersion forces (LDFs)?

Accepted Answer

Intermolecular forces between all molecules, caused by temporary dipoles

Question 3

Why do London dispersion forces form?

Accepted Answer

Electrons in adjacent atoms randomly move in a way that makes them temporary dipoles

Question 4

What makes London Dispersion Forces stronger?

Accepted Answer

More contact between molecules

Increasing polarizability (size of electron cloud)

Question 5

What is polarizability?

Accepted Answer

How easy it is for a molecule to become polarized

(more electrons, larger electron cloud, and pi bonding increase polarizability)

Question 6

What is the difference between van der Waals forces and London Dispersion Forces?

Accepted Answer

van der Waals forces are types of forces that occur because of dipole-dipole interaction

London Dispersion Forces are a type of van der Waals forces

Question 7

What is a dipole moment?

Accepted Answer

A measurement of the seperation of two opposite electrical charges

Created by atoms in a molecule sharing electrons unequally

Question 8

What are dipole-dipole forces?

Accepted Answer

Intermolecular forces between the positive end of a polar molecular and the negative end of another polar molecule

(only polar molecules)

Question 9

What makes dipole-dipole forces stronger?

Accepted Answer

Magnitudes of the dipoles and their relative orientation

Question 10

What are dipole-induced-dipole forces?

Accepted Answer

Intermolecular forces between polar and nonpolar molecules

(polar molecule induces a dipole in the nonpolar molecule)

Question 11

What makes dipole-induced-dipole forces stronger?

Accepted Answer

The polar molecule having a dipole with a greater magnitude

Question 12

What are ion-dipole forces?

Accepted Answer

Intermolecular forces between ions and polar molecules

Question 13

What is hydrogen bonding?

Accepted Answer

A strong intermolecular interaction between hydrogen atoms bonded to highly electronegative atoms (N, O, F) and another highly electronegative atom (N, O, F)

Question 14

What interactions occur in large biomolecules?

Accepted Answer

Noncovalent interactions between different molecules or different regions of the same large biomolecule

Question 15

What happens to IMFs when a substance undergoes a phase change?

(e.g., melting to boiling)

Accepted Answer

The IMFs are broken or formed

Question 16

How do IMFs influence a substance's properties?

Accepted Answer

Weak IMFs = High vapor pressure

Strong IMFs = High boiling point, High melting point

(correlation with melting point is more subtle)

Question 17

How do IMFs influence ionic solids?

Accepted Answer

Ions have strong interactions, leading to low vapor pressure, high melting point, and high boiling point

Question 18

Why do covalent network solids have high melting points?

Accepted Answer

They have strong covalent interactions in their 2/3-D networks

Question 19

Why do molecular solids have a low melting point?

Accepted Answer

They have weak covalent IMFs between the individual molecules

Question 20

What do particle diagrams look like for solids, liquids, and gases?

Accepted Answer

Solid is tightly packed; Liquid is more loose; Gas is free flowing

Question 21

What is vapor pressure?

Accepted Answer

The pressure exerted by a liquid in equilibrium with its liquid state

Question 22

What increases vapor pressure?

Accepted Answer

Increased temperature

Increased number of molecules?

Question 23

What are crystalline solids?

Accepted Answer

Solids where particles are arranged in a regular, 3D structure

(opposite of amorphous solids)

Question 24

What are amorphous solids?

Accepted Answer

Solids where particles do not have a regular, orderly arrangement

(opposite of crystalline solids)

Question 25

How do particles cause pressure?

Accepted Answer

By physically hitting the walls of the container

Question 26

What is Boyle's Law?

Accepted Answer

As pressure increases, volume decreases

Question 27

What is Charle's Law?

Accepted Answer

The volume of an ideal gas is proportional to its temperature

Question 28

What is Gay-Lussac's Law?

Accepted Answer

As pressure increases, temperature increases

Question 29

What is the Combined Gas Law?

Accepted Answer

The combination of Boyle's, Charles', and Gay-Lussac's laws

(ignore any variables that aren't addressed)

Question 30

What is the Ideal Gas Law?

Accepted Answer

The pressure and volume of a gas are proportional to the amount of gas and the gas's temperature

Question 31

What is Dalton's law of partial pressure?

Accepted Answer

Total pressure equals the pressure of each individual gas

(you can add two gases with different pressures, and the result will have a pressure that is the sum of their pressures)

Question 32

What is Avogadro's Law?

Accepted Answer

Equal volumes of gases have the same number of molecules

Question 33

What is Kinetic Molecular Theory (KMT)?

Accepted Answer

A model of how gas particles move

Particles are in constant, rapid, random motion

Question 34

What is a Maxwell-Boltzman distribution?

Accepted Answer

A probability distribution of the speeds of particles

There are more particles at a speed where the line is higher

Changes with temperature

Question 35

What is the average kinetic energy of a particle?

Accepted Answer

Proportional to its mass and velocity squared

Question 36

What does increased temperature do to the kinetic energy of particles in a sample?

Accepted Answer

Increased temperature = Increased kinetic energy

Question 37

What is the Ideal Gas Law flawed?

Accepted Answer

It assumes gases are ideal (no volume, no attractive forces, elastic, etc.)

In reality, gases have properties that make them less than ideal

Question 38

What causes deviations from the Ideal Gas Law?

Accepted Answer

Interparticle attractions between gas molecules

Conditions close to condenstation

High particle volumes

High pressures

Question 39

When do gases behave most ideally?

Accepted Answer

High temperatures, low pressures

Question 40

What is a solution?

Accepted Answer

A homogenous mixture made from two or more substances

(can be solids, liquids, or gases)

Question 41

What is molarity?

Accepted Answer

The amount of a substance in a certain volume of a solution

Question 42

What is the equation for molarity?

Accepted Answer

M = molar concentration

n = moles of solute

v = liters of solution

Question 43

What should you include in a particulate representation of a solution?

Accepted Answer

Molecules, their rotations, their polarities, etc.

Question 44

What are particulate diagrams?

Accepted Answer

Diagrams that communicate the structure/properties of a solution with an image

Question 45

What is solubility?

Accepted Answer

A substance's ability to be dissolved

Question 46

What is miscibility?

Accepted Answer

The property for two liquids to form a homogenous mixture when mixed together

Question 47

What is the difference between solubility and miscibility?

Accepted Answer

Solubility generally refers to a solid solute dissolving in a liquid solvent

Miscibility refers to a liquid solute dissolving in a liquid solvent

Question 48

Which substances tend to be miscible/soluble in each other?

Accepted Answer

Substances with similar intermolecular interactions

Question 49

How can liquids be separated?

Accepted Answer

Chromatography and distillation

(filtration doesn't work)

Question 50

What is chromatography?

Accepted Answer

A technique used to separate dyes and pigments

Question 51

What is the stationary phase in chromatography?

Accepted Answer

The substance that remains in place (the chromatography paper)

Question 52

What is the mobile phase in chromatography?

Accepted Answer

The substance that moves (generally some type of alchohol)

Question 53

What are the steps to chromatography?

Accepted Answer

Dye containing a mixture of pigments is spotted at the bottom of the chromatography paper

End of the paper is placed into a solution (mobile phase)

As the mobile phase moves up the stationary phase, the components of the mixture separate

Question 54

What happens to components that are more attracted to the mobile phase in chromatography?

Accepted Answer

More attracted = Move further up the paper

(polar = polar substances move further up, and vice versa)

Question 55

What are  values in chromatography?

Accepted Answer

A measure used to compare compounds and how far they traveled

Question 56

What is distillation?

Accepted Answer

A process used to separate liquids with different boiling points

Question 57

How does distillation work?

Accepted Answer

Liquids are heated in a distillation apparatus

Mixtures with higher vapor pressures (weaker IMFs) will evaporate first

Vapors are cooled and re-condense in a collecting chamber

Question 58

What happens when an atom absorbs/emits a photon?

Accepted Answer

The atom's energy increases/decreases by the amount of the energy in the photon

Question 59

How is wavelength related to frequency in a wave?

Accepted Answer

As wavelength increases, frequency decreases

Question 60

How is the energy of a photon related to its frequency?

Accepted Answer

As frequency increases, energy increases

Question 61

What is the Beer-Lambert law?

Accepted Answer

Absorption is proportional to the molar absorptivity, path length, and concentration

Unit 2: Intermolecular Forces & Properties, AP Chemistry Flashcards