AP®︎ Chemistry: Unit 3 Flashcards

Between molecules: dispersion, dipole-dipole, hydrogen bonding, ion-dipole; within particles: covalent, ionic, metallic bonding.

Attractions from Coulombic interactions between temporary, fluctuating dipoles in all atoms and molecules.

How easily an electron cloud is distorted; it increases with more electrons, larger size, and pi bonding.

Greater surface contact between molecules increases dispersion attractions by allowing more electron-cloud interactions.

Dispersion is one specific weak attraction; van der Waals is a broader category and not synonymous.

Attractions between a polar molecule and a nonpolar molecule whose electron cloud becomes temporarily distorted.

Attractions between an ion and the oppositely charged end of a polar molecule.

Opposite charges aligned closer give stronger attraction; like-charge alignment gives weaker or repulsive interactions.

Between separate molecules or between different regions of the same large molecule containing suitable N, O, or F sites.

Hydrogen bonding, ionic attractions, dipole interactions, and dispersion forces within or between large biomolecules.

Generally ion-dipole and hydrogen bonding exceed dipole-dipole, while dispersion varies with size and polarizability.

A permanent molecular dipole creates attractions between polar molecules when opposite partial charges align.

A momentary uneven electron distribution that creates partial charges in an atom or molecule.

A strong intermolecular attraction between H covalently bonded to N, O, or F and a lone pair on N, O, or F.

Solids with particles arranged in a regular, repeating pattern called a crystal lattice.

Diagrams showing atoms, ions, or molecules arranged to reveal forces and solid structure.

Stronger attractions give lower vapor pressure and generally higher boiling and melting points.

Ionic: ions; molecular: molecules with IMFs; covalent network: bonded networks; metallic: metal atoms with mobile electrons.

Shifting layers place like charges adjacent, causing repulsion and fracture.

Diamond is a hard 3D network insulator; graphite is layered, soft, and electrically conductive.

Crystalline solids of cations and anions with high melting points, brittleness, and conductivity only when ions move.

Solids of metal cores in a sea of mobile, delocalized valence electrons.

They conduct heat and electricity and are malleable and ductile because mobile electrons maintain bonding.

Metal mixtures form substitutional or interstitial structures, and interstitial atoms make the lattice more rigid.

Solids of discrete molecules held by intermolecular forces, usually with low melting points and poor conductivity.

Solids of atoms covalently bonded in 2D or 3D networks, giving very high melting points and hardness.

Their shapes and properties depend on noncovalent interactions within one molecule or between molecules.

A crystal lattice is a regular, repeating three-dimensional arrangement of particles in a crystalline solid; the unit cell is the smallest repeating structural unit that builds the entire lattice.

Solid: fixed shape and volume; liquid: fixed volume only; gas: neither fixed shape nor volume.

Crystalline solids have ordered 3-D particle arrangements; amorphous solids lack long-range regular order.

Particles stay in fixed positions and only vibrate, with no overall translational motion.

Solid structure depends on how strongly particles attract and how efficiently they can pack together.

Particles remain close together but move continuously, collide often, and slide past one another.

The ability of particles in a substance, especially a liquid or gas, to flow past one another.

For one substance, solid and liquid phases usually have similar molar volumes because particles stay closely packed.

Particles are far apart, move constantly in straight lines, and experience minimal intermolecular attractions.

These variables change particle spacing and collision frequency in a gas.

The extent to which a substance's volume decreases when pressure is applied.

Mixing is extremely slow in solids, slow in liquids, and rapid in gases.

A liquid minimizes surface area; stronger intermolecular forces increase it, while higher temperature decreases it.

A liquid's resistance to flow increases with stronger intermolecular forces and decreases with higher temperature.

Attractions within a liquid and to surfaces determine capillary action and meniscus shape.

PV = nRT, relating pressure, volume, moles, and temperature for an ideal gas.

P in atm, V in L, n in mol, T in K, and R = 0.08206 L·atm/mol·K.

Conditions of 1 atm pressure and 273.15 K temperature.

Pressure comes from gas particles colliding with the walls of their container.

At constant temperature, pressure and volume are inversely related: P1V1 = P2V2.

At constant pressure, volume and temperature are directly related: V1/T1 = V2/T2.

At constant volume, pressure and temperature are directly related: P1/T1 = P2/T2.

At constant pressure and temperature, volume is directly proportional to moles: V1/n1 = V2/n2.

P1V1/T1 = P2V2/T2, combining pressure, volume, and temperature when moles stay constant.

Total pressure equals the sum of each gas's partial pressure in a mixture.

The pressure exerted by one gas component in a mixture, independent of other gases.

The ratio of moles of one gas to total moles in a mixture.

For gas A, PA = XA × Ptotal, where XA is its mole fraction.

P, V, T, and n can be graphed to show direct or inverse proportional relationships.

Atmospheric pressure under standard conditions is 1.00 atm, 760 torr, 760 mm Hg, or 101.3 kPa.

Temperature in Celsius is converted to Kelvin by adding 273.15.

All particles in a sample of matter are always moving in random directions.

Collisions in which particles transfer energy without any net loss of total kinetic energy.

Gas particles occupy very little space compared with the total volume of the container.

Ideal gas particles neither attract nor repel one another between collisions.

Faster particles collide with container walls more often and more forcefully, increasing pressure.

A model describing gases as tiny particles moving randomly with negligible volume, no forces, and elastic collisions.

A graph showing particle energies or speeds, where higher temperature broadens the curve and shifts it right.

The average kinetic energy of particles is directly proportional to the Kelvin temperature, and at the same temperature all gases have the same average kinetic energy.

Real-gas pressure is lower than ideal pressure because attractions reduce wall-collision frequency and force.

At very high pressure, real gases occupy more volume than ideal gases predict.

Real gases deviate because particles attract each other and occupy finite volume.

Low temperature, high pressure, polarity, and larger size make gases less ideal.

This real-gas model corrects pressure for attractions and volume for particle size.

A mixture with uniform composition whose macroscopic properties are the same throughout the sample.

A mixture with nonuniform composition whose macroscopic properties vary from one location to another.

Solutions can be solid, liquid, or gas, as long as composition is uniform throughout.

Dissolved in water, written as aq in a chemical equation.

Solvation is solvent attraction around solute particles; hydration is this process specifically in water.

Molarity uses total solution volume, not just the volume of the solvent.

Lowering concentration by adding solvent while keeping the amount of solute constant.

Use M1V1 = M2V2 because moles of solute stay constant during dilution.

Moles of solute per liter of solution, used to calculate amount, volume, or concentration.

The dissolved substance is the solute, and the dissolving medium is the solvent.

A particle-level diagram showing component amounts, distribution, and interactions in a solution.

Show concentration by the number of solute particles per equal volume of solution.

Dilute has few solute particles, concentrated has many, saturated has the maximum dissolved amount.

Concentrations should be compared using the same volume so particle counts are meaningful.

A layer of solvent molecules surrounding and stabilizing a dissolved particle.

One forms ions in water and conducts electricity; the other forms no ions and does not.

One dissociates completely into ions in water; the other dissociates only partially.

The separation of an ionic compound or electrolyte into ions in solution.

Show intact molecules, with water oriented toward polar regions if intermolecular attractions exist.

An ion attracts polar water molecules, with oxygen toward cations and hydrogens toward anions.

Ionic solutes separate into ions, while molecular solutes remain intact particles in solution.

Separates an insoluble solid from a liquid by passing the mixture through a porous barrier.

Separates mixture components by different attractions to a mobile phase and a stationary phase.

Stationary phase stays fixed; mobile phase moves and carries dissolved substances through or across it.

Paper uses cellulose, TLC uses coated silica plates, and column uses packed solid adsorbent in a tube.

More polar substances usually stick more to polar stationary phases and travel shorter distances.

The separation pattern showing component positions after chromatography, used to compare relative polarity.

Separates liquids by heating so the more volatile component vaporizes first and then condenses.

Simple uses one vaporization-condensation step for larger boiling-point differences; fractional uses many steps for closer boiling points.

Weaker intermolecular forces give higher vapor pressure and lower boiling point, so that component distills first.

The ratio of a substance’s travel distance to the solvent front’s distance.

The maximum amount of solute that dissolves in a given solvent under specific conditions.

The ability of two liquids to mix completely and form one homogeneous phase.

At maximum dissolved solute, below that amount, and above that amount in an unstable state, respectively.

Increasing pressure increases the solubility of gases, but has little effect on solids or liquids.

Solubility is greatest when solute-solvent attractions closely match or exceed particle-particle attractions.

A graph showing how a substance's solubility changes with temperature.

Energy that travels through space as oscillating electric and magnetic waves.

The idea that light behaves as both a wave and a particle.

The full range of electromagnetic radiation, ordered by wavelength or frequency.

The study of how matter absorbs, emits, or interacts with electromagnetic radiation.

Patterns formed when matter absorbs specific wavelengths or emits photons at specific wavelengths.

Wavelength and frequency are inversely related and connected by c = λν.

Microwaves cause rotational changes, infrared causes vibrational changes, and UV-visible causes electronic changes.

E = hν, relating photon energy to frequency through Planck's constant.

The proportionality constant 6.626 × 10^-34 J·s used in E = hν.

Electrons change energy levels by absorbing or emitting photons with matching energy.

Frequency and wavelength are inversely related, and higher frequency means higher photon energy.

Electrons are emitted from metals only when light reaches a minimum frequency.

A discrete packet of electromagnetic energy absorbed or emitted by matter during a transition.

The spectrophotometer component that isolates a narrow band of wavelengths from white light.

A transparent sample holder whose width sets the light-travel distance, usually measured in centimeters.

I0 is light entering the sample; I is light leaving after some has been absorbed.

A unitless measure of how much light a sample absorbs at a given wavelength.

A wavelength-specific constant showing how strongly a substance absorbs light, symbolized by epsilon.

A = epsilonbc, relating absorbance to molar absorptivity, path length, and concentration.

With wavelength and path length constant, absorbance increases linearly as concentration increases.

Solutions absorb light best in the color opposite their observed color on the visible spectrum.

Rearrange A = epsilonbc to c = A divided by epsilon times b.

A method using an instrument to measure transmitted light and determine sample absorbance.

The wavelength at which a substance absorbs most strongly, giving the greatest measurement sensitivity.