Which statement best defines a molecule?

A molecule is defined as a group of two or more atoms that are chemically bonded together. This bonding can occur between atoms of the same element, such as in molecular oxygen (O2), or between different elements, as seen in water (H2O). The key aspect of a molecule is that it exhibits distinct chemical properties resulting from the specific arrangements and types of atoms involved in the bonds.

Understanding the nature of a molecule is central to the study of chemistry, as molecules are the building blocks of chemical compounds and reactions. By recognizing that molecules consist of multiple atoms bonded together, one can appreciate how they play a critical role in forming the structures of matter at a microscopic level and influencing chemical behavior.

In contrast, the other statements misrepresent the nature of molecules; they either describe single atoms, independent atoms, or limit their definition to specific types of compounds that do not encompass the broader definition of a molecule, which can include both elements and compounds.