20 Our Surroundings 



the energy of motion. But neither our bodies, nor any other 

 living things, can develop more energy than already exists in some 

 form in the materials taken into them. 



The Basis of All Science. We have just read about matter 

 and energy. Remember that nothing exists, whether it be a 

 stone, a plant, or an animal, that is not made of matter. Remem- 

 ber, too, that any change, such as of position, shape, size, color, 

 temperature, can never be brought about without the use of 

 energy. Matter and energy are all that are needed to make up 

 the entire earth, everything on it, and even all growth and motion. 



SUMMARY 



All substances consist of matter which is either organic or in- 

 organic. 



Matter occurs in three states, gaseous, liquid and solid. 



A property of matter is some quality of that matter. 



A property may be general or special, physical or chemical. 



The law of the conservation of matter declares that matter 

 can never actually be destroyed, though it can be changed 

 from one form to another. 



The most striking characteristic of matter is the fact that it is 

 constantly subject to changes. These changes are either physical 

 or chemical. In a physical change the nature of matter remains 

 the same ; in a chemical change it is altered. All living matter is 

 especially subject to chemical change. 



Changes in matter are brought about by the action of some 

 form of energy, such as heat, light or motion. 



The law of the conservation of energy declares that energy 

 cannot be created or destroyed, although it may change its form. 



All living things must have energy in order to live. 



The source of all energy is the sun. 



FACT AND THOUGHT QUESTIONS 



1. Define matter. State the difference between organic and inorganic 



matter. 

 2 Give several examples of inorganic matter seen on the way to school. 



3. Name several examples of organic matter in the classroom. 



4. Define states of matter. 



