What is the smallest unit of matter?

The smallest unit of matter is an atom. An atom serves as the fundamental building block of all matter, including elements and compounds, making it essential to understand in the context of chemistry and physics. Each atom consists of a nucleus, containing protons and neutrons, surrounded by electrons. Even though molecules and compounds consist of multiple atoms bonded together, they are not the smallest unit as they are made up of groups of atoms.

A chemical element is a pure substance that cannot be broken down into simpler substances by chemical means and consists of only one type of atom, but it does not represent the smallest unit of matter by itself. Understanding atoms is crucial for grasping the concepts of chemical reactions, bonding, and the structure of matter in general, making them central to various scientific disciplines, including dental radiation safety.