14 Our Surroundings 



matter. Water, air, stone, gold and iron are examples of inorganic 

 matter. 



States of Matter. Matter exists in different forms. We are 

 familiar with water as we see it in a pond or in a dish. It can 

 easily be poured from one container to another. We call it a 

 liquid. A liquid is a freely-moving fluid which tends to take the 

 shape of its container. 



If heated sufficiently, water boils, changes to steam and passes 

 off into the air. Steam can be kept in a bottle, but the top must 

 be covered tightly and the temperature of the bottle must be kept 

 high enough to prevent the steam changing back to water again. 

 Steam is a gas. A gas is a light, air-like substance which tends to 

 expand indefinitely. 



If a pail of water has been left where the temperature is low 

 enough, we notice that the water has changed to ice. Ice is a 

 solid. A solid is a body so rigid that it will keep its shape when 

 left without a container to hold it in place. 



These three different conditions, liquid, gaseous, and solid, in 

 which matter can exist, we call states of matter. It is believed 

 that all matter could be made to exist in each of these three forms 

 by adding or removing sufficient heat. As yet, however, man has 

 been unable to produce the degree of heat or cold necessary to 

 change the state of certain substances. 



Properties of Matter. A property of a substance is some 

 peculiar quality it possesses. A property is either physical or 

 chemical. A physical property is one that can be recognized by 

 the senses. Taste, color, size, odor are physical properties. A 

 chemical property is one that accounts for a change in the com- 

 position of the substance. Wood burns when set on fire and is 

 changed to ashes and gas. The ability to burn is a chemical 

 property of wood. 



A property of matter may be general or special. It is a general 

 property when it is common to all kinds of matter, whether in 

 solid, liquid or gaseous state. It is a special property when it 

 shows itself in one or more kinds of matter but not in all kinds. 

 All kinds of matter take up room or space. This is a general 

 property commonly called extension. For example, water, whether 



