CHEMICAL PHENOMENA 59 



posed of mercury and oxygen. It was found possible, 

 however, by heat to overcome the attraction which the 

 mercury and oxygen had for each other and thus to 

 decompose the compound -which they had formed by 

 their union. 



Questions 



1. Name two physical properties of iron. 



2. Name one chemical property of iron. 



3. Give an example of a mechanical mixture. 

 Explain why the example given is a mechanical 

 mixture. 



4. Is iron sulphide a mechanical mixture or a 

 chemical compound? Why? 



5. Define the term chemical element. 



6. How many elements are there? 



7. Name ten elements. What is the symbol for 

 each? 



8. What are the differences between chemical 

 synthesis and chemical analysis? 



9. Give two examples of chemical synthesis. 

 Two of chemical analysis. 



10. What is the name given to the force which 

 holds elements together when they form compounds? 



11. Through what agencies may this force be 

 overcome ? 



12. State several conditions under which elements 

 will unite. 



