You can tell whether silicon is an elementary substance or a compound by counting the number of atomic symbols in its chemical formula. An atomic symbol consists of either one capital letter or a capital letter followed by one or two lowercase letters.
The chemical formula for silicon contains one atomic symbol: Si. So, the formula tells you that silicon is composed of only one chemical element.
Since silicon is composed of only one chemical element, silicon is an elementary substance.
Complete the statement.
Silicon is ().
A: an elementary substance
B: a compound