<|system|>
Complete the statement.
Copper is ().
A: an elementary substance
B: a compound</s>.
<|user|>
Can you answer based on context?
<|assistant|>
You can tell whether copper is an elementary substance or a compound by counting the number of symbols in its chemical formula. A symbol contains either one capital letter or a capital letter followed by one or two lowercase letters.
The chemical formula for copper is Cu. This formula contains one symbol: Cu. So, the formula tells you that copper is made of one chemical element.
Substances made of only one chemical element are elementary substances. So, copper is an elementary substance.