Which statement correctly defines a molecule?

Which statement correctly defines a molecule?

• A. The smallest unit of matter
• B. Two or more atoms bonded together
• C. A substance formed when atoms share electrons
• D. The energy required to start a reaction

Answer: (C)

A molecule is formed when atoms bond together to make a stable, discrete unit. The way this happens most often is by atoms sharing electrons, creating covalent bonds. When electrons are shared, the bonded atoms stay connected as one particle that can be studied as a single substance—the molecule. This is why describing a molecule as a substance formed when atoms share electrons captures how molecules come to be: the shared electrons are what hold the atoms together in a specific arrangement. The other ideas aren’t defining features of a molecule: a single atom is not a molecule, and activation energy describes what starts a reaction rather than what a molecule is.

A molecule is formed when atoms bond together to make a stable, discrete unit. The way this happens most often is by atoms sharing electrons, creating covalent bonds. When electrons are shared, the bonded atoms stay connected as one particle that can be studied as a single substance—the molecule. This is why describing a molecule as a substance formed when atoms share electrons captures how molecules come to be: the shared electrons are what hold the atoms together in a specific arrangement. The other ideas aren’t defining features of a molecule: a single atom is not a molecule, and activation energy describes what starts a reaction rather than what a molecule is.