Section 1 Energy Changes
A. Energy—ability to cause change
B. Energy transformation—energy changes from one form to another without any being lost or gained
C. Energy due to motion is kinetic energy.
1. An object’s kinetic energy depends on its speed and mass.
2. When objects collide, kinetic energy can be transferred.
D. Potential energy—stored energy due to an object’s position
E. Potential energy can be transformed to kinetic energy and kinetic energy can be converted to potential energy.
F. Law of conservation of energy—energy cannot be created or destroyed; it can only change form
1. Total amount of energy in the universe never changes.
2. Kinetic energy can be converted to heat energy.

DISCUSSION QUESTION:
What does an object’s kinetic energy depend on? its speed and mass

Section 2 Temperature
A. Temperature—measure of the average kinetic energy of an object’s atoms
B. Temperature is measured with a thermometer.
1. Fahrenheit scale—freezing point of water is 32° and boiling point is 212°
2. Celsius scale—freezing point of water is 0° and boiling point is 100°
C. Heat—transfer of energy from one object to another due to a difference in temperature
1. Heat moves from warmer objects to cooler ones.
2. Flow of heat stops when the temperature of two objects is the same.
D. Water is unusual because it takes a large amount of heat to raise its temperature; water’s temperature does not change as much as surrounding air or land.
E. Heat can be transferred in three ways.
1. Conduction—transfer of energy by collisions between atoms; usually occurs in solids
2. Convection transfers heat when particles move between objects or areas that differ in temperature; most common in gases and liquids.
3. Energy transferred by waves is radiation.

DISCUSSION QUESTION:
How is the kinetic energy of an object’s atoms measured? As temperature, using a thermometer

Section 3 Chemical Energy
A. Chemical reactions release energy.
1. Compounds are broken down or new compounds are formed in a chemical reaction.
2. Energy in chemical bonds is a form of potential energy called chemical energy.
3. In every chemical reaction, energy transformations occur.
B. To break chemical bonds, energy must be added; when chemical bonds form, energy is released.
1. Endothermic reactions—chemical reactions that absorb energy
2. Exothermic reactions—chemical reactions that release energy
3. Chemical reactions occur at different rates; a catalyst changes the rate of chemical reaction without its own structure being changed.

DISCUSSION QUESTION:
How do endothermic and exothermic chemical reactions differ? endothermic—absorb energy;
exothermic—release energy