What is a molecule?

A molecule is defined as a chemical bonding of atoms, which corresponds to the correct answer. Molecules are formed when two or more atoms join together through chemical bonds, which can involve covalent bonds (where atoms share electrons) or ionic bonds (where atoms transfer electrons). This bonding results in the formation of distinct entities that can range from simple diatomic molecules, such as oxygen (O2) and hydrogen (H2), to complex organic molecules such as glucose (C6H12O6).

The concept of a molecule is fundamental in chemistry, as it constitutes the smallest unit of a chemical compound that retains its chemical properties. Understanding molecules allows for the exploration of how they interact, combine, and react in various chemical processes, making it an essential aspect of both biology and chemistry.

Conversely, the other options pertain to different biological and chemical concepts that do not accurately describe a molecule. A combination of cells refers to the structural organization of living organisms, while a group of tissues relates to the biological organization of similar cells working together. An atomic structure focuses on the arrangement of protons, neutrons, and electrons within an atom itself, rather than the bonding between multiple atoms that creates a molecule.