Which statement correctly defines molecules?

Which statement correctly defines molecules?

• A. Molecules are groups of two or more atoms bonded together, representing the smallest fundamental unit of a chemical compound.
• B. The smallest unit of an element.
• C. A battery of ions in solution.
• D. A reaction pathway.

Answer: (A)

A molecule is formed when two or more atoms bond together, creating a discrete unit that has the properties of a substance. This captures the essential idea that bonding links atoms to make a distinct entity, whether the atoms are of the same element (like O2 or N2) or different elements (like H2O or CO2). The smallest unit of an element is an atom, not a molecule, which is why that option isn’t the best definition. A battery of ions in solution refers to ions dissolved in a solvent, not a discrete bonded unit. A reaction pathway describes how a reaction proceeds, not the actual unit that defines a substance’s composition. So, two or more bonded atoms as the smallest identifiable unit of a substance best defines what a molecule is.

A molecule is formed when two or more atoms bond together, creating a discrete unit that has the properties of a substance. This captures the essential idea that bonding links atoms to make a distinct entity, whether the atoms are of the same element (like O2 or N2) or different elements (like H2O or CO2). The smallest unit of an element is an atom, not a molecule, which is why that option isn’t the best definition. A battery of ions in solution refers to ions dissolved in a solvent, not a discrete bonded unit. A reaction pathway describes how a reaction proceeds, not the actual unit that defines a substance’s composition. So, two or more bonded atoms as the smallest identifiable unit of a substance best defines what a molecule is.