What is the smallest unit of matter?

The smallest unit of matter is an atom. Atoms are the fundamental building blocks of all elements and the basic units from which all substances are composed. Each atom consists of a nucleus made up of protons and neutrons, surrounded by electrons that orbit around the nucleus.

Understanding atoms is crucial in the study of chemistry and physics, as they are the simplest form of matter that retains the properties of an element. Molecules consist of two or more atoms bonded together, while compounds are formed from two or more different elements chemically combined. Elements represent specific types of atoms defined by the number of protons in their nuclei. Therefore, an atom stands at the very base of matter's hierarchy, making it the smallest indivisible unit of matter.