Chapter 5: Thermal Effects

tiny particles

In atoms, there are ________ called electrons.

volume of gas

As the temperature rises, the ________ increases the gas expands.

On the Celsius scale

0 degrees Celsius (0 °C) is defined as the melting point of pure ice

NOTE

Both ice and water should be pure for accurate reading

Range

is the difference between maximum and minimum temperatures

Describe solid.

Fixed shape and volume. Its particles are held closely together by strong forces of attraction. They vibrate backwards and forwards but cannot change positions.

Describe liquid.

Fixed volume but can flow to fill any shape. The particles are close together and attract each other, but they vibrate so vigorously that the attractions cannot hold them in fixed positions, and they can move past each other.

Describe gas.

No fixed shape or volume and quickly fills any space available. Its particles are well spaced out, and virtually free of any attractions. They move about at high speed, colliding with each other and the walls of their container.

State kinetic theory.

Matter is made up of tiny particles which are constantly in motion. The particles attract each other strongly when close but the attractions weaken if they move further apart.

State brownian motion.

Smoke particles drift through the air, wobble about in zig-zag paths. Wobbling, wandering motion of pollen grains in water.

Define thermal energy.

Also known as heat. The energy transferred when a hot material is in contact with a cold material.

Define specific heat capacity.

The energy that must be transferred to an object to increase its temperature. [No change in state, just change in temperature]

Define latent heat of fusion.

The energy absorbed when ice (solid) turns to water (liquid). [No change in temperature, just change in state]

Define latent heat of vaporization.

The energy absorbed when water (liquid) turns to steam (gas). [No change in temperature, just change in state]

Define conduction.

Main method for heat to transfer in solids.

Give examples of good heat conductors.

Examples:

• metals

• silicon

• graphite

Define convection.

Main method for heat to transfer in fluids (liquids and gases)

Define radiation.

Main method for heat to transfer in vacuum (no solids, no liquids and no gases)

What are emitters?

Surface good for sending out thermal radiation.

Give example of good heat emitters and absorbers

Black surfaces.

What are absorbers.

Surface good for taking in thermal radiation.

What are reflectors.

Surface good for reflecting thermal radiation.

Give examples of good heat insulators.

Examples:

• glass,

• water,

• wood,

• rubber.

How do materials conduct heat?

In atoms, there are tiny particles called electrons. Most are firmly attached, but in metals, some are loose' and free to drift between the atoms. When a metal is heated, these free electrons speed up. As they move randomly within the metal, they collide with atoms and make them vibrate faster. In this way, thermal energy is rapidly transferred to all parts.