Temperature and Heat Unit Exam Review

What is the Particle Theory?

The particle theory is how scientists explain what the particles of a substance are doing as it is heated.

What is Thermal Energy?

Thermal energy is heat energy. It is describe by the amount of movement of a substances particles.

E.g.. More movement, more thermal energy

We know that a substance has a lot of thermal energy if:

It is hot Expansion has occurred A change of state is taking place

The particles of a substance with a lot of thermal energy would look like:

Expansion and Contraction

Expansion is the increase in volume of a substance

Contraction is the decrease in volume of a substance

Expansion is caused by adding thermal energy

Contraction happens when thermal energy is removed

Changes of State

Changes of state are the different forms that matter can take. Also known as phases of matter.

Generally, there is more thermal energy present in a gas than a solid.

When a substance is changing state, its temperature stays constant until is totally changes state. This is because all of the energy is going to towards changing the state, and not increasing the temperature.

Graph

Radiation, Conduction, Convection Radiation: the transfer of energy in the form

of waves Conduction: the direct transfer of energy Convection: the continuous circulation in a

fluid in which thermal energy is transferred

Something can become heated when it is not in direct contact with the heat source due to thermal radiation. The energy moves through the air in the form of waves

The difference between conduction and convection is that conduction describes how something is heated when it is in direct contact with the heat source.

Convection describes how thermal energy cause circular currents in the air or water.

We can prevent heat loss in our homes by minimizing the amount of heat lost through convection, conduction and radiation.

Examples: insulation, new windows, caulking around windows, door sweep all help to stop moving warm air from escaping

A fire place can provide radiant heat and solar panels could be used to gather heat radiation from the sun

Heat mats utilize conduction to transfer thermal energy to floor tile for heated floors.

Good luck on Wednesday!