HEAT / THERMAL ENERGY

Phase Changes

-Melting, Freezing, Evaporation, Boiling, Condensation, Sublimation

Temperature:

absolute zero: the temperature at which molecular motion stops.

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

http://www.brainpop.com/science/energy/temperature/

Heat

the energy transferred between objects that are at different temperatures

Heat is always transferred from the object that has the higher temperature to the object that has the lower temperature

http://www.brainpop.com/science/energy/heat/

When matter is heated, the molecules react by…..

-Speeding up

-Spreading out

Thermal: heat Expand: to get bigger

When matter is cooled, the molecules react by…..

-Slowing down

-Contracting

This is known as thermal expansion-The increase in volume (size) due to added heat.

Conduction

Transfer of heat / energy through direct contact

-Occurs best in solids

Conductors Insulators

Metal Objects

Water

Wood

Glass

Cotton

Rubber

Air

Convection

Transfer of heat / energy through liquids and gases

-Involves circular currents based on density of cooler / warmer matter

Radiation

Transfer of heat / energy through open space

-Radiate: To Give Off

Light Energy radiated from the sun

Only about half the energy from the sun reaches Earth. The other half is either reflected away or is absorbed by other factors

The Greenhouse Effect

Warming that results when solar radiation is trapped by the atmosphere; caused by atmospheric gases that allow sunshine to pass through but absorb heat that is radiated back from the warmed surface of the earth

OZONE

Ozone is a gas made up of three oxygen atoms (O3). It occurs naturally in small (trace) amounts in the upper atmosphere (the stratosphere).

Ozone protects life on Earth from the Sun’s ultraviolet (UV) radiation.

Pollution is depleting it – upsetting the natural balance of “good” ozone at the stratospheric level of the atmosphere

Brainpop greenhouse effect