 Total energy in molecules of a substance including  a) kinetic E of moving molecules  b) potential E stored in chemical bonds

 Average kinetic energy per molecule  Average speed of molecule  KE = ½ m V 2 m = mass V = velocity  Velocity or speed is most important  0 velocity = absolute 0….no motion of particles

 Flow of thermal Energy from hot to cold  Transfer of kinetic energy from one molecule to another 

 1) Energy can not be created or destroyed  only converted from one form to another  or transferred from one place to another  2) Heat energy flows from high temperature areas to low temperature areas only

 No net flow of heat energy because all areas are the same temperature  Heat flows from hot to cold until….  Thermal equilibrium is reached….  Then it just passes back and forth  Still moving so still heat!

 Measure their own temperature  Put thermometer in water. Heat flows  Molecules of alcohol speed up and expand or  slow down and contract  Thermal equilibrium between thermometer and water causes red line to stop moving.  meter meter

 Temperature is measured in…  o Celsius  Heat is measures in….  calories  1 calorie =  the amount of heat needed  to raise the temp of 1ml H 2 O  by 1 o C

 The Calories in your food are Calories,  They are actually Kilocalories =  the amount of heat needed to warm up 1,000 ml of H 2 O by 1 o C

 It takes more heat energy to increase the temperature of some substances.  We say those substances have a high specific heat.  Water has very High specific heat  Specific heat is measured in cal/ml/ o C  or cal/g/ o C

 High specific heat warms up slower AND  Cools off slower   More massive  at/page2.cml at/page2.cml

 1) Conduction – objects touch, direct heat transfer from warm object to cold object  2) Convection – heat transferred by flowing molecules  3) Radiation – electromagnetic waves =  Infrared light waves  heat waves, not visible

 Metals are good conductors because their  electrons are loosely held (can flow)  Non-metals hold their electrons tightly so are poor conductors called…  insulators

 Good conductors at room temperature feel:  cold to the touch because….  heat is leaving your hand quickly.  Poor conductors don’t feel as cold because heat is leaving more slowly

 warm, fast moving molecules rise carrying heat with them  (they expand & become less dense)

 Electromagnetic waves  =light waves  Not visible  Heat waves

 Lowest energy = solid  a) strongest intermolecular forces  b) molecules vibrate in place so  definite shape and volume  Medium energy = Liquid  a) weaker intermolecular forces allow  molecules to flow around each other  so no definite shape  b) still to low energy for molecules to  break away completely and expand  so definite volume

 Highest energy = gas  a) weakest intermolecular forces  b) molecules can flow & expand  c) no definite shape or volume

 Change in amount of thermal energy cause molecules to move in different ways  Higher energy =  weaker intermolecular forces  as molecules expand  Mass does not change  Density changes

 Solid  Liquid  Gas  low high  x = Heat energy (per mole) needed  to be in that phase

 A-B  Warming ice  Add E, Temp  B-C  Melting  Add E, no ∆ Temp  E used to break intermolecular forces so molecules can flow

 C-D  Warming water  Add E, Temp  D-E  vaporization  Add E, no ∆ Temp  E used to break intermolecular forces so molecules can expand

 Boiling  Bubbles of gas form at bottom of liquid  Evaporation  High energy molecules break loose from surface of fluid

 F-E  Cooling steam  Remove E, Temp  E – D  condensing  Remove E, no ∆ Temp  Loss of E lets intermolecular forces reform & hold molecules together

 D-C  Cooling water  Remove E, Temp  C-B  freezing  Remove E, no ∆ Temp  Loss of E strengthens intermolecular forces so molecules can only vibrate