Oxygen 263 



carbon dioxide, consisting of one atom of carbon com- 

 bined with two atoms of oxygen". Hence such an 

 equation would be read thus : 



One atom of carbon combines with the oxygen in 

 one molecule of oxygen to form one molecule of carbon 

 dioxide. 



Further, since we have means of determining the 

 relative weights of the atoms of the various elements, 

 the above equation also shows that 12 unit weights 

 (grams, ounces, tons, . . . ) of carbon combine with 

 32 similar unit weights of oxygen to form 44 unit 

 weights of carbon dioxide. 



The complete discussion of this matter of chemical 

 symbols, formulae, and equations, and their proper use, 

 is beyond the scope of this book. Hence they will not 

 be introduced in later chapters unless it is desired to 

 lend special emphasis to some important consideration 

 thereby. 



The student is advised to abstain from the indis- 

 criminate use of the various symbols and formulae as 

 mere abbreviations for the names of the different 

 substances, in order to avoid the confusion which 

 frequently arises from using them wrongly. 



QUESTIONS 



1. Describe as fully as you can a method of obtaining a sample 

 of oxygen from the air. 



2. Discuss the suitability or otherwise of the name oxygen for 

 that element. 



3. Try to classify all the oxides already mentioned under one 

 of the heads given in the latter part of the chapter. 



4. How would you endeavour to find out whether magnesium 

 forms an acidic or a basic oxide ? Write out what you think would 

 be the chemical equations representing any changes involved in your 

 method. 



