Which of the following best describes a molecule?

A molecule is best defined as two or more atoms bonded together. This definition encompasses a wide variety of substances, from simple diatomic molecules like oxygen (O2) to complex molecules like proteins and DNA, which consist of many atoms bonded in intricate arrangements.

Molecules are distinct entities that maintain specific chemical properties based on the types of atoms that compose them and how they are bonded. When atoms bond together, they form molecules through chemical bonds, which can be covalent or ionic, among others. This bonding results in the formation of stable units that can exist independently, a key characteristic of what we refer to as a molecule.

Understanding the nature of a molecule is fundamental in chemistry, as it lays the foundation for more advanced concepts like molecular structure, chemical reactions, and the behaviour of substances in different states of matter. This concept differentiates molecules from individual atoms or ions, which do not depict the combined nature of multiple atoms functioning as a single unit.