# What is the "degree of unsaturation" with respect to organic molecules?

Alkanes have a general formula of ${C}_{n} {H}_{2 n + 2}$. These are saturated molecules. An olefin, an alkene, has ONE so-called degree of unsaturation. If there is an olefinic bond, OR a ring junction, the formula drops from ${C}_{n} {H}_{2 n + 2}$ to ${C}_{n} {H}_{2 n}$, i.e 2 hydrogen LESS than the saturated formula.