Parts of the Atom and Isotope Symbol

A model of the Solar System compared to a model of an atom

The structure of an atom is quite similar to the structure of the Solar System. The nucleus of the atom is in a similar position compared to the position of the Sun. Electrons act very similar to planets, orbiting around the nucleus in an electron cloud. So far, you have learned that a relatively small, dense nucleus holds a positive charge and contains an atom's mass. The negatively-charged electrons swarm around the nucleus. In this topic, you will learn how the particles in the nucleus determine the identity of the element.

Essential Questions

• What are the parts of an atom, and what do they explain about an element?
• What is an isotope, and how are isotopes notated?