

ELEMENTS AND COM 



the elements, as copper, silver, and gold, hax^e character- 

 istic colors. Some compounds owe their value entirely to 

 their color, and are used for paints and dyes. 



4. Odor and taste. The odor and taste of an element 

 or compound are physical properties which are character- 

 istic of the element or compound. 



5. Electrical characteristics. Elements and compounds 

 have definite electrical properties. They are either good 

 or poor conductors of electricity, and offer a large or small 

 amount of resistance to the passing of an electric current. 



The way in which a substance responds to pressure, 

 water, heat, and cold, depends upon its physical proper- 

 ties, and the physical properties in turn are modified by 

 these agencies. 



In the study of the elements and their compounds, the 

 physical properties are also included because our knowl- 

 edge of chemistry would be incomplete without consider- 

 ing the physical as well as the chemical properties of 

 substances. 



14. Chemical Properties. In addition to the physical 

 properties, each element and compound has definite chem- 

 ical properties. This is because the molecules of the 

 different elements are unlike in character and some of the 

 elements and compounds are more readily affected by 

 chemical agencies than are others. The molecules of 

 compounds are made up of atoms of different kinds which 

 impart different properties to the molecule. Copper, for 

 example, has different chemical properties from gold. It 

 will dissolve more readily in acids, tarnish in the air, and 

 be acted upon more rapidly by other bodies than will 



