Degrees of Freedom

So far every molecule has been treated as if it can only translate -- move bodily from one point to another. Real molecules made of two or more atoms can also rotate about an axis and vibrate along their bonds, and each of these independent ways of storing energy is called a degree of freedom. Counting a molecule's degrees of freedom correctly turns out to be exactly what is needed, in Section 9.4, to predict how much heat energy a particular type of gas needs in order to warm up by a given amount -- monatomic, diatomic and triatomic gases genuinely behave diffe …