| − | {{merge|Chemical compound}}
| + | A '''chemical formula''' is a description which tells the number and type of each [[element]] in a [[compound]]. A chemical formula consists of the symbols of each element in a compound each followed by the number of that type of element in a subscript. For example, [[methane]] is composed of one [[carbon]] atom (symbol C) and four [[hydrogen]] atoms (symbol H). Methane's chemical formula is thus CH<sub>4</sub>. |
| | + | The order of the elements in the chemical formula is sometimes written in such a way to clarify the structure of the chemical compound. For example, take a molecul which has two carbon atoms, six hydrogen atoms and one oxygen atom. The chemical formula could be written as C<sub>2</sub>H<sub>6</sub>O, however this does not clarify the structure of the molecule. C<sub>2</sub>H<sub>5</sub>OH lets the chemist know that there is a [[hydroxyl]] group, OH in the molecule. Now the chemist knows that the compound is an alcohol, ethanol. To clarify the structure even more, it could be written as CH<sub>3</sub>CH<sub>2</sub>OH, to show that three hydrogens are bonded to the first carbon, which is itself bonded to a second carbon. The second carbon is bonded to two hydrogens and a hydroxyl group. |