Most molecules are made up of two or three or many different kinds of atoms. Water is made up of hydrogen and oxygen atoms. Oil and gas are molecules. They are made up of atoms of carbon and hydrogen, so they are called hydrocarbons. Don't get mixed up, our English language can confuse us.
Cooking oils are quite different from the oils that come out of an oil well.
They are made by plants and animals, and you can eat them. The gasses and the oils that come out of an oil well are often called petroleum. You can also call them hydrocarbons. This is a carbon atom. These little guys are hydrogen atoms.