The Three States of Matter
Matter exists in three physical states: solid, liquid and gas. A block of ice has both a definite shape and a definite volume; it does not need side support to maintain its shape. Neither its shape nor its volume can be easily changed by external pressure. Ice is a solid. All solids have a definite volume and a definite shape.
If the temperature of ice is raised sufficiently, it melts and becomes a liquid, water. Water occupies a definite volume, although its volume differs from that of ice. But water requires side support. Without this support, it spreads in all directions. If we wish to confine water, we must use a container, then water takes the shape of this container. But because water occupies a definite volume, it has one free surface. Liquids have a definite volume, but take the shape of their containers.
If the temperature of water is raised sufficiently, it boils and becomes steam. Steam is an example of matter in the gaseous state. In order to confine steam, a closed container is needed. Steam completely fills any container, no matter what its size, because steam has no definite volume. Since steam can be held only in a completely closed container, it has no free surface and so it takes the shape of the container. Gases have neither a definite volume nor a definite shape.
QUESTIONS
1. Give 3 examples of elements illustrating the 3 states of the matter.
2. Can we turn a solid into gas? Explain how.
3. a) Give the differences between the 3 states of the matter.
b) Do they have something in common?
4. Complete the text by filling the gaps.
"Solids, liquids and gases are physical..... of the..... If.....ice, it becomes water. And if we boil water, it becomes..... Without a.... we cannot confine water; if not, it.....