| Elemental properties and reactions are determined only by electrons in the outer energy levels. Electrons in completely filled energy levels are ignored when considering properties. Simplified Bohr diagrams which only consider electrons in outer energy levels are called Lewis Symbols. |
| A Lewis Symbol consists of the element symbol surrounded by “dots” to represent the number of electrons in the outer energy level as represented by a Bohr Diagram. The number of electrons in the outer energy level is correlated by simply reading the Group number. Lewis symbols for oxygen, fluorine, and sodium are given in the diagram on the left. |
Lewis Symbols for the elements of the second period. Correlate the number of dots with the group number.  |
