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A '''molecule''' is a group of two or more atoms linked together to form one unit. They are linked together by chemical bonds.  The four types of chemical bonds are [[Covalent Bond|covalent]], [[ionic bond|ionic]], [[hydrogen bond|hydrogen]] or [[van der Waals' bond|van der Waals]]'.

A '''molecule''' is a group of two or more [[atom]]s linked together by [[covalent bond]]s to form one unit. A molecule can have as few as two atoms, or as many as several thousand, as in a [[polymer]].

A molecule can consist of a single element only, or more than one.

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 [[gas]]es, such as [[oxygen]] (O₂), [[hydrogen]] (H₂) and [[flourine]] (F₂). Single element compounds also include man-made compounds such as [[buckminsterfullerene]]s, which are "balls" of 60 carbon atoms, as well as natural compounds like [[graphite]], [[diamond]]s, and many [[metal]]s.

The list of single-element compounds is relatively short, mostly represented by gases which usually form stable compounds of two atoms, although there are some interesting [[man-made]] examples such as "Bucky balls", which are pure [[carbon]], with the atoms arranged in a geodesic pattern.

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.

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