Chapter 11

Whew! It's Hot!

Temperature and thermal energy

Temperature – measure of the average kinetic energy of the particles in an object

Thermal energy – the TOTAL energy of the particles that make an object

Heat – the transfer of energy between objects at different temperatures

1)Temperature is a measure of the average kinetic energy of the particles in an object

2)The more kinetic energy particles have the higher the temperature will be

3) Temperature (unlike thermal energy) is not determined by the amount of substance.

BUT – if you have more of the substance you will have MORE thermal energy because you have more particles

4) Thermal expansion is the increase in volume of a substance due to an increase in temperature.

It happens because the particles spread away from each other when heated

When particles spread apart the substance becomes less dense

5) The three temperature scales we use are

Fahrenheit

Celsius

Kelvin

Section 2: Heat

1) Heat is the transfer of thermal energy between objects that are at different temperatures.

2) Thermal Energy is the TOTAL energy of particles that make up a substance.

It depends on temperature and amount of the substance.

3) The three ways thermal energy is transferred:

ConductionConvectionRadiation

4) Conduction is the transfer of thermal energy through direct contact between objects

5) Items that transfer thermal energy well are called conductors (metals)

Items that DO NOT conduct energy well are called insulators

Every atom is physically bonded to its neighbors in some way. If heat energy is supplied to one part of a solid, the atoms vibrate faster. As they vibrate more, the bonds between atoms are shaken more. This passes vibrations on to the next atom, and so on:           

Eventually the energy spreads throughout the solid. The overall temperature has increased.

6) Convection: transfer of thermal energy by movement in a liquid or gas.

7) Radiation is the transfer of thermal energy through matter or space as electromagnetic waves.

Examples: light and heat from a fire

Temperature vs Thermal energy:What’s the difference?

Thermal Energy vs Heat: What’s the difference?

• Click on the address below for more info on physical and chemical changes

• Address: http://schools.bcsd.com/fremont/5th_sci_matter_physical_changes.htm