Science / Chemistry / Molecule: The smallest particle of an element or compound that retains the chemical properties of the element or compound. A molecule is a collection of chemically bound atoms with characteristic composition and structure. Making or breaking bonds in a molecule changes it into a new molecule. Ionic compounds are not composed of molecules, because there is no distinct collection of ions that are chemically bound in the crystal.
Science / Biology / Macromolecules: Large molecules made up of many small organic molecules that are often referred to as monomers; e.g., carbohydrates, lipids, proteins, and nucleic acids. Macromolecules are polymers of monomers. MORE
Science / Chemistry / Diatomic Molecule: A molecule that contains only two atoms. All of the noninert gases occur as diatomic molecules; e. G. Hydrogen, oxygen, nitrogen, fluorine, and chlorine are H2, O2, N2, F2, and Cl2, respectively. MORE