Valence Electrons

Electrons in atoms can be found in orbitals. These orbitals are found in shells. Think about a jawbreaker. A jawbreaker has multiple layers all the way down to the center. Each layer can be thought of as a shell of electrons. The electrons that are in the outermost shell, the valence electrons, are most accessible to other atoms and molecules.

The only flavor you taste on a brand new jawbreaker is the one that is on top, the outermost layer. Using this analogy, you can see why it is the outermost electrons, the valence electrons, that are responsible for the chemical reactivity of an atom.

Picture of a Jawbreaker

The jawbreaker model we have used to distinguish valence electrons is a good starting place for understanding the location of electrons within an atom, but a more complicated model that involves orbitals provides an even better understanding of electrons in atoms.