These molecules can be both short or long, but, in
general, they have a simple structure. Many are
long, straight, or branched chains of carbon
molecules with attached hydrogen atoms. Some
common smaller examples include pentane and
octane, which are refined into components
that make up gasoline.

These oil molecules form carbon-based ring
structures and are named because they give off an
aromatic smell. Many, like benzene, are toxic and
can cause cancer in humans.

Resins are complicated molecules that include
nitrogen, oxygen, or sulfur. They have a thick, tacky
consistency and are used in paints, rubber, and
concrete.

The largest and heaviest compounds are massive,
complicated molecules. This residual oil material
includes the thick asphalt used to pave roads.