Most molecules are composed of two or more elements, but they can also be composed of multiple atoms from the same element. Single element, bimolecular molecules include many elementary gases, such as oxygen (O2), hydrogen (H2) and fluorine (F2). Single element compounds also include man-made compounds such as buckminsterfullerenes, which are "balls" of 60 carbon atoms, as well as natural compounds like graphite, diamonds, and many metals.
Molecules are described in many ways, depending on the information that needs to be conveyed. The simplest is simply a list of the elements with subscripts representing the number of that element's atoms that are present. Often part of the molecule is listed separately in order to show some of its properties. There are more complex, but still text based, ways of "describing" the molecule's entire structure. We also use three dimensional "ball and stick" or "space filling" diagrams to show the complete physical arrangement of the atoms in the molecule.