2Kinetic Theory An explanation of the behavior of molecules in matter 3 basic assumptionsAll matter is composed of small particles (atoms, molecules, and ions)These particles are in constant, random motionThese particles are colliding with each other and the walls of their container
3Thermal Energy The total energy of a material’s particles Kinetic energy + potential energyAVERAGE KINETIC ENERGY=TEMPERATUREFaster moving particles = higher temp.Slower moving particles =lower temp.Absolute zero = C (particle motion is so slow that no additional thermal energy can be removed)
4Solid State Has a definite shape and volume Particles are closely packed together and vibrating in placeParticles have a geometric arrangement
5Liquid State Has a definite volume, but no definite shape Particles slip out of their ordered arrangement and are able to move past each otherStill some attractive forces
6Liquid StateMelting point – The temp. at which a solid begins to liquifyHeat of fusion – The amount of energy required to change a substance from the solid phase to the liquid phase at its melting point
7Gas State No definite shape or volume Particles have enough kinetic energy to overcome the attractive forces between themParticles bounce and collide, filling their container
8Gas StateBoiling point – the temperature at which the pressure of the vapor in the liquid is equal to the external pressure acting on the surface of the liquidHeat of vaporization – the amount of energy required for the liquid at its boiling point to become a gas
9Gas State Evaporation Boiling Occurs at the surface of a liquid Can occur at temperatures below the boiling pointMust have enough kinetic energy to escape the attractive forces of the liquidOccurs throughout a liquidOccurs at a specific temp.
10DiffusionSpreading of particles throughout a given volume until they are uniformly distributedOccurs in solids and liquids, but most rapidly in gasesFrom high concentration to low concentration
11Heating Curves Shows temp. change as thermal energy (heat) is added Temp. remains constant during melting and while boilingAll energy is used to overcome attractive forces
12Thermal ExpansionAn increase in the size of a substance when the temp. is increasedSolids (gaps in sidewalks)Liquids (thermometers)Gases (hot air balloons)
13The Strange Behavior of Water Water molecules have highly positive and negative areasAs they cool, molecules align themselves by charge, so empty spaces occur in the structureWater expands as it goes from liquid to solidIce is less dense than water (that’s why it floats!)
14Plasma StateMatter consisting of positively and negatively charged particles (neural charge overall)Very high energy hard collisions of molecules electrons stripped offEx - stars, lightning bolts, neon tubes, etc.
15Amorphous Solids Not all solids have a definite melting point Some merely soften and turn into liquid over a range of temps.They lack the ordered structures of crystalsEx - glass and plastic (long, chainlike molecules)
16Liquid CrystalsStart to flow during the melting phase similar to a liquid, but they do not lose their ordered arrangement completelyHighly responsive to temperature change and electric fieldsEx - LCD displays of watches, clocks, and calculators
17Changes in Thermal Energy Experiment Create a time/temperature tableFill your beaker halfway with ice and cold waterUse your thermometer to measure the temperature of the water (DO NOT TOUCH THE THERMOMETER TO THE SIDES OR BOTTOM OF THE BEAKER) Record this temp. as time zeroPlace your beaker on a hot plate over medium heatMeasure the temperature every minute and record it in your tableCreate a graph using your data.Write a paragraph describing what is happening in your graph.