Chemical Change and Energy 



299 



and two parts of oxygen. When you put this with 

 baking soda, which is made of one part of the metal 

 sodium, one part of hydrogen, one part of carbon, and 

 three parts of oxygen, you get water and carbon dioxid 

 gas and a kind of salt called sodium acetate." Or, 

 more briefly, " If you put baking soda with vinegar, 

 you get water, a gas called carbon dioxid, and a salt." 

 You can see how much shorter the chemist's way of 

 writing it is. 



Some elements you already know. Here is a list of 

 some elements that you are already pretty well ac- 

 quainted with. The abbreviation is put after the name 

 for each. This list is only for reference and need not 

 be learned. 



Aluminum (Al) 

 Carbon (C) 



Chlorine (Cl) 



Copper (Cu) 



Gold (Au) 



Hydrogen (H) 



Iodine 



Iron 

 Lead 



Mercury 

 Nickel 

 Nitrogen 

 Oxygen 



(I) 



(Fe) 



(Pb) 



(Hg) 



(Ni) 



(N) 



(O) 



Charcoal, diamonds, graphite (the lead in a 

 pencil is graphite), hard coal, and soot are 

 all made of carbon. 



A poison gas that was used in the war. 



The lightest gas in the world ; you got it from 

 water in the last experiment and will get it 

 from an acid in the next. 



It is a solid ; what you use is iodine dissolved 

 in alcohol. 



This is another name for quicksilver. 



About four fifths of the air is pure nitrogen. 



This is the part of the air we use in breathing. 

 You got some out of water, and you will 

 have it to deal with in another experi- 

 ment. 



