2 EnergyPotential Energy: Stored Energy If you heat a substance, that substance will store some of that energy in its particles Kinetic Energy: Energy of Motion
3 Kinetic Energy: Increases in kinetic energy result in increases in temperature Heat added to a system that is not stored as potential energy will be absorbed by the particles which will increase the particles’ kinetic energyAbsolute Zero (0 K): The temperature at which the motion of particles theoretically ceases and the particles have no kinetic energy
4 Directly proportional to the kinetic energy of the particles Kelvin Scale: Reflects the relationship between temperature and average kinetic energyDirectly proportional to the kinetic energy of the particlesK = C + 273
5 All matter consists of tiny particles that are in constant motion Kinetic TheoryAll matter consists of tiny particles that are in constant motion
6 Intermolecular Forces Hydrogen Bonding: The large partial charge resulting in an extremely strong dipole-dipole force between hydrogen of on molecule (+) and the F, O or N of another molecule (-)One of the strongest intermolecular forcesDipole-Dipole Forces: Attractions between opposite charges of neighboring permanent dipolesHappens between polar moleculesDispersion Forces: A force of attraction between induced dipolesInduced dipoles occur when a temporary dipole occurs (the e- move to one side of an atom simply through their natural movement)Can happen between nonpolar moleculesStrength
8 SOLIDLIQUIDGASIonic, Metallic or Molecular Bonds (Strong Bonds between atoms)Atoms, ions or molecules are packed tightly togetherParticles vibrate around fixed pointsCrystalline or Amorphous SolidsDo not flowCondensed state of matter (pressure has little effect on a solid)Only slightly compressibleHigh densityExtremely slow diffusion (only occurs at surface)Definite volumeDefinite shapeMolecules or AtomsIntermolecular forces keep the particles in a liquid close togetherIntermolecular forces reduce the amount of space between the particlesCondensed state of matter (pressure has little effect on a liquid)Can flow (a fluid)Does not expand to fill the containerAssumes the shape of the containerSlow diffusionNo definite shapeParticles are small, hard spheres with insignificant volumeParticles are far apart with empty space between themNo attractive or repulsive forces between particlesMotion of one particle is independent of the restMotion of particles is rapid, constant and in straight line paths until they collidePerfectly elastic collisions (kinetic energy remains constant)Can be compressedLow densityFills container completelyAssumes shape of containerRapid DiffusionNo definite volume nor shape
9 Vacuum: An empty space with no particles and no pressure Gas Pressure: The force exerted by a gas per unit surface area of an objectCaused by the collisions of the moving gas particles with an objectBarometer: Device that is used to measure atmospheric pressureAtmospheric Pressure: Results from the collisions of atoms and molecules in air with objectsGasses
11 Units of Pressure 1 atm = 760 mm Hg = 101.3 kPa Pascal (Pa): SI unit of pressureatmosphere: Pressure required to support 760 mm Hg in a mercury barometer at 25Cmm Hg: Unit on a barometerStandard Temperature & Pressure (STP): Temperature of 0C and 1 atm
12 LIQUIDS Vapor Pressure: A measure of the force exerted by a gas above a liquidAt equilibrium: The rate of evaporation of the liquid equals the rate of condensation of the vapor
13 MANOMETER: Measures the vapor pressure of a contained liquid
14 Affect of Temperature on Vapor Pressure An increase in temperature of a contained liquid will increase the vapor pressure because the kinetic energy will increase resulting in more particles escaping the surface of the liquid.
15 VISCOSITY A liquids resistance to motion Liquids with stronger intermolecular forces will have higher viscositiesWater’s viscosity is relatively high due to its hydrogen bondingLower temperatures = higher viscosity
16 Greater in liquids with strong intermolecular forces SURFACE TENSIONImbalance of attractive forces at the surface of a liquid that causes the surface to behave as if it had a thin film across itGreater in liquids with strong intermolecular forces
17 SOLIDSCrystals: The particles are arranged in an orderly, repeating, 3-dimensional pattern called a crystal latticeThe shape of the crystal reflects the arrangement of the particles within the solidUnit Cell: The smallest group of particles within a crystal that retains the geometric shape of the crystal
19 Change of State Conversion of a substance from one of three physical states of matter toanother.A.k.a: Phase ChangeAlways involves: A change in energy
20 Energy & State ChangesGases have the most potential energy, solids the least
21 VAPORIZATION: The change of state from a liquid to a gas Evaporation: Molecules at the surface of a liquid escape and enter the gas phaseBoiling: When the vapor pressure of the liquid is equal to the atmospheric pressure, bubbles of gas form and escape the liquid.Evaporation rates increases with increases in temperature because the increase in energy allows more molecules to escape the surface of the liquidThe molecules remaining behind in the liquid are lower in energyBoiling Point: The temperature at which the vapor pressure of the liquid becomes equal to the atmospheric pressureNormal Boiling Point: The boiling point of a liquid at a pressure of kPa (normal atmospheric pressure)
22 If atmospheric pressure increases, the temperature needed to reach the boiling point will also increase. If atmospheric pressure decreases, the temperature needed to reach the boiling point will also decrease.
23 CONDENSATIONThe change of state from a gas to a liquid
24 FREEZING The change of state from a liquid to a solid. Freezing Point: Thetemperature atwhich the solidand liquid forms ofa substance existin equilibrium
25 MELTING The change of state from a solid to a liquid Melting Point: The temperature at which a solid changes into a liquidEquals: The freezing point
26 Sublimation: The change of state from a solid to a gas Deposition: The change of state from a gas to a solidTypically occurs with molecular solids with weak intermolecular forces.
28 HEATING CURVEDuring a state change, the temperature remains constant while the potential energy increases/decreases. This will occur until the state is completely changed and then kinetic energy will begin to increase/decrease again.
29 Phase DiagramRelates the state of a substance to its temperature and pressure.Triple Point: The only set of conditions at which all three phases can exist in equilibrium with one anotherFor water, the triple point is 0.016C and 0.61 kPa/ atm