Created by Gilbert Lewis, Lewis Dot Diagrams are simple models to represent the arrangement of electrons in atoms that explain and predict empirical formulas.
The model is simply the symbol for the ele![enter image source herement representing the nucleus plus all the electrons except the valence electrons.
The valence electrons (represented by the last digit of a group number on the periodic table), change and are shown as dots around the central symbol , with the entire diagram showing (for an atom) a net charge of zero.
These diagrams are an extremely useful model to help describe how atoms bond.
To draw Lewis symbols for main groups of atoms:
Write the element symbol to represent the nucleus and any filled energy levels of the atom.
Add a dot to represent each valence electron.
Start by placing valence electrons singly into each of four valence orbitals (represented by the four sides of the element symbol).
4.If additional locations are required for electrons once each orbital is half-filled, start filling each of the four orbitals with a second electron until up to eight valence electrons have been represented by dots.
For example: Oxygen has 6 valence electrons .
Electron Energy Level Diagram of an Oxygen Atom:
Since Oxygen has 6 valence electrons, to represent the atom in a Lewis Dot Diagram you would take the central atom, which is O and surround it with 6 dots.
It is important to understand that Lewis symbols do not mean that electrons are dots or that they are stationary. The four sides of the atomic symbol just represent the four valence level space regions (orbitals) that may be occupied by electrons. The dots simply keep count of how many electrons are in each orbital (or not).
Source: Nelson Chemistry Textbook.