What is the smallest particle of an element?

The smallest particle of an element is an atom. An atom is defined as the basic unit of matter that retains the properties of that element. It consists of a nucleus, made up of protons and neutrons, surrounded by electrons that orbit the nucleus. Each element on the periodic table is characterized by its distinct atomic structure, determined by the number of protons in the nucleus, which defines the element itself.

In contrast, a molecule consists of two or more atoms that are chemically bonded together, often resulting in a compound. An ion refers to an atom or molecule that has gained or lost one or more electrons, thus acquiring an electric charge. A compound, meanwhile, is a substance formed when two or more different types of atoms bond together in a fixed ratio.

Understanding these definitions clarifies the concept of the atom as the fundamental building block of an element, distinguishing it from larger constructs such as molecules and compounds.