No, a molecule cannot consist of only one atom. By definition, a molecule is a combination of two or more atoms held together by chemical bonds. These atoms can be of the same element (as in diatomic molecules like oxygen, O2, or hydrogen, H2) or different elements (such as water, H2O, composed of two hydrogen atoms and one oxygen atom).
Molecules are formed when atoms interact and share electrons to achieve a more stable configuration. This bonding can occur through various types of chemical bonds, including covalent bonds, ionic bonds, or metallic bonds. The resulting molecule has distinct chemical and physical properties that are different from its constituent atoms.
However, a single atom can exist on its own, and it is referred to as an atom rather than a molecule. Atoms are the basic building blocks of matter and retain their individual identity, although they can form molecules when combined with other atoms.