In class 9, students learn about the basic structure of an atom, which is the fundamental piece of matter and the basic building block of all matter. An atom consists of three tiny particles called subatomic particles: protons, neutrons, and electrons. The protons and neutrons make up the center of the atom called the nucleus, while the electrons fly around above the nucleus in a small cloud. Protons carry a positive charge, electrons carry a negative charge, and neutrons are neutral. An atom contains equal numbers of protons and electrons and therefore overall has no charge. The number of protons in the nucleus of an atom is the atomic number for the chemical element. Different elements atomic numbers are found in the Periodic Table of Elements. The basic structure of an atom includes a tiny, relatively massive nucleus, containing at least one proton and usually one or more neutrons. The discovery of atoms was a revolutionary beginning to a new and detailed world of Science.