1. Lewis Structure
Diagrams

2. The Lewis structure model (or “Lewis dot diagram”) is a great way to represent the element’s potential for reacting with another substance. It shows only the outermost energy level of electrons – these are called valence electrons.

3. Valence Electrons are the electrons in the outer most energy level of an atom; they determine how an element will react with other substances.

4. For Example: Sulfur is element #16
For Example: Sulfur is element #16. That means there are 16 protons, and 16 electrons. Here is what the Bohr model looks like: S

5. The valence electrons are located in the outer shell
The valence electrons are located in the outer shell. These are the ones that are used to draw the Lewis Structure Diagram Sulfur has 6 valence electrons. S

6. S
So, if we were to draw a Lewis Structure, you would put only the valence electrons (as dots) on the outside of the element symbol. You can put a maximum of 2 dots on each “side” of the element name.

7. S
You start by looking at the edges of the chemical symbol as a box. Imagine that there are 8 spaces available for the electrons.

8. Then fill in the dots (valence electrons) one at a time.

9. S
Elements all want to have a FULL outer shell. So, the two empty spaces make the Sulfur atom feel empty and in need of more. It will look for another atom who may have some electrons to “share” (more on this later).

10. Ar
Argon is in the “Noble Gas” Family. Notice that the outer shell is completely full. Argon doesn’t “Need” anyone – it feels satisfied just like it is.

11. O H H

12. O H H
Notice how Oxygen had two empty spaces (it only has 6 valence electrons). Hydrogen only has 1 valence electron. When the elements bond to each other, forming a molecule, it makes the elements feel “happy” or complete. You have just faked-out Oxygen – it thinks it has 8 valence electrons (because it is sharing two from the 2 Hydrogens). The two Hydrogen molecules are also “faked-out”, because they now think their outer shell is full (with 2 electrons) because of the ones they are “sharing” with Oxygen.