Lesson 2: Atomic Structure

In the first lesson, you were briefly introduced to the concept of structure and function. In this lesson you will take a closer look at atomic structure by developing an atomic model. The atomic model is a representation of the structure of an atom. By building a basic model, you will learn more specific details about the particles that make up the atom: the electron, the proton, and the neutron. The electron is a negatively charged particle with a small mass — it is found in all matter. It orbits the center, or nucleus, of the atom. The neutron is a particle that has zero electrical charge (also called a neutral charge) and a mass approximately equal to that of a proton. A proton is a particle that is a component of all atoms and carries a positive charge equal to that of the electron's negative charge. The nucleus (plural = nuclei) is the positively charged central region of an atom that consists of protons and neutrons. The nucleus contains most of the mass of the atom.

This lesson has three parts. The first two introduce you to the basics of atomic structure. The third part is a quick historical investigation that will give you insight into how scientists discovered that the atom was indivisible. During this lesson, keep in mind that all matter is made up of atoms or combinations of different atoms.