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        | organizes information about the elements and their properties |  | 
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        | average mass of one atom of an element---protons + neutrons |  | 
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        | the number of protons in the nucleus of an atom---the number of protons identifies the element |  | 
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        | elements in the same column; have similar physical and chemical properties |  | 
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        | a material that can be pounded into shapes |  | 
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        | a material that can be pulled out, or drawn, into a long wire |  | 
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        | elements that can transmit heat and electricity easily |  | 
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        | attracted to magnets or can be made into magnets |  | 
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        | the process of reaction and wearing away |  | 
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        | a mixture of metals:  brass is an alloy of copper and zinc |  | 
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        | elements that lack most of the properties of metals; located to the right of the zigzag line |  | 
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        | when molecules contain 2 atoms |  | 
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        | elements in Group 18; do not ordinarily form compounds with other elements |  | 
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        | metalloid (semiconductor) |  | Definition 
 
        | elements that are on the zigzag line; have some characteristics of metals and some of nonmetals; semiconductors are substances that under some conditions can conduct electricity (like a metal) and other conditions cannot (like a nonmetal) |  | 
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