What are the smallest units of elements that retain all original properties?

The smallest units of elements that retain all original properties are atoms. Atoms are the fundamental building blocks of all matter and are composed of protons, neutrons, and electrons. Each element is defined by its unique type of atom, which determines its chemical properties and behavior. For instance, a single hydrogen atom maintains the characteristics of hydrogen, such as its reactivity and ability to form bonds.

Cells, while integral to biological systems, are significantly larger and composed of many atoms, molecules, and organelles. Molecules consist of two or more atoms bonded together and represent combinations of different elements or the same element, yet do not correspond to the basic properties of those elements themselves. Ions are charged particles that arise from atoms losing or gaining electrons but, by themselves, do not maintain the full set of properties of neutral atoms. Thus, it is clear that atoms are indeed the smallest units that retain all the distinct qualities of the elements they represent.