What is defined as two or more atoms chemically joined together?

A molecule is defined as two or more atoms chemically joined together. This formation can consist of the same type of atoms, as seen in oxygen gas (O2), or different types of atoms, such as in water (H2O). The key aspect of a molecule is the chemical bond that holds the atoms together, making it a distinct entity with its own properties.

In contrast, ions are charged particles that result from the loss or gain of electrons, which means they are not necessarily formed by the bonding of multiple atoms. Suspensions and emulsions refer to mixtures rather than compounds; a suspension consists of solid particles dispersed in a liquid, while an emulsion is a mixture of two liquids that typically do not combine, like oil and water. Thus, the definition of a molecule clearly distinguishes it from these other concepts in chemistry.