5-4 Solids, Liquids, & Gases

Matter has three phases, or states.  They are solids, liquids, and gasses.  A solid has a definite shape and volume.  A liquid has a definite volume, but it takes on the shape of the container it is in.  Gas (vapor) takes on both the shape and volume of the container it is in.

You know the different states of water.  It is ice in its solid state.  It is water in its liquid state.  It is steam as a gas.  No matter what phase or state, the matter is exactly the same (H2O).

By adding or removing energy matter can change phases.  When a phase change occurs, as when water changes to ice, no new type of matter is produced.  Remember, only the state (phase) of the matter has been changed.

The melting point of a solid is the temperature at which it changes to a liquid.  Water melts at 0 degrees C.  0 degrees C is also the freezing point of water.  Freezing is the change from liquid to a solid.

Water doesn't always get smaller when it cools.  Initially water does contract (get smaller) as it gets cooler, however at 4 degrees C it begins to expand (get larger).  The colder it gets, the more it expands, until it reaches its freezing point of 0 degrees C.  Ice is lighter than water, so it floats on top.

Directions: Answer the questions about states of matter.

A (vapor) takes on both the shape and volume of the container it is in.

A has a definite shape and volume.

A has a definite volume, but it takes on the shape of the container it is in.

Water in its solid state is .

Water in its liquid state is .

Water in its gas state is .

Matter can change phases by adding or removing .

Water melts and freezes at degrees C.

The point of a solid is the temperature at which it changes to a liquid.

Freezing is the change from liquid to a .

Contract means to get .

Expand means to get .