Posted by iampatpatt on Friday, April 16, 2010 Under: Science
Changing state
Introduction
Solid, liquid and gas are called the three states of matter. Materials can be changed from one state to another by heating or cooling.
Water moves around the environment in the water cycle.
States of matter
Solid, liquid and gas are called the three states of matter.
Materials can be changed from one state to another by heating or cooling.
Heating
If ice (solid) is heated, it changes to water (liquid). This change is called melting.
If water (liquid) is heated, it changes to water vapour (gas). This change is calledevaporation.
Cooling
If water vapour (gas) is cooled, it changes to water (liquid). This change is calledcondensing.
If water (liquid) is cooled, it changes to ice (solid). This change is called freezing.
The water cycle
Water on the earth is constantly moving. It is recycled over and over again. This recycling process is called thewater cycle.
a. Water evaporates into the air The sun heats up water on land, and in rivers, lakes and seas and turns it into water vapour. The water vapour rises into the air.
b. Water vapour condenses into clouds Water vapour in the air cools down and changes back into tiny drops of liquid water, forming clouds.
c. Water falls as rain The clouds get heavy and water falls back to the earth in the form of rain or snow.
d. Water returns to the sea Rain water runs over the land and collects in lakes or rivers, which take it back to the sea. The cycle starts all over again.
