What is the smallest unit of elements?

The smallest unit of an element is an atom. Atoms are the fundamental building blocks of matter, and each element is defined by its unique type of atom. For example, a single hydrogen atom is the smallest unit of hydrogen, representing that element in its most basic form. Atoms consist of a nucleus, containing protons and neutrons, surrounded by electrons. Regardless of whether they are in a free state or part of a molecule or compound, atoms retain the properties of the element they represent.

In contrast, a molecule is formed when two or more atoms bond together, representing a grouping of atoms rather than the smallest individual unit. A compound is a substance composed of two or more different types of atoms, indicating that it is a combination of several atoms together. An ion refers specifically to an atom that has gained or lost electrons, resulting in a charge; thus, while it’s a modification of an atom, it is not the foundational unit of an element itself.