Final answer:
Atoms form the most basic unit with unique properties, which combine to form molecules. Molecules arrange into organelles, which together in a cellular structure form cells, the smallest unit of life. Cells group into tissues, tissues into organs, organs into organ systems, and finally, organ systems form a complete organism.
Step-by-step explanation:
Neutrons, protons, and electrons make up atoms, the smallest particles with unique chemical properties. Two or more atoms make up a molecule. Molecules form together to make organelles, much larger complexes like mitochondria, lysosomes, and centrioles. The smallest unit of life, cells consist of multiple organelles and macromolecules. Collections of like cells performing a similar function, tissues are divided into four major categories. Multiple different tissue types together are called organs and likewise work together to perform similar actions. In organ systems several organs work together to carry out a similar function. A complete, single organism represents the largest division of hierarchical organization.