How to Draw Lewis dot diagrams

Member

By dasbootjoe
User-Submitted Article

Article Rating:

(14 Ratings)

Draw Lewis dot diagrams

Lewis dot diagrams are used to show how elements bond together in a molecule. You can show how any element bonds with another simply by understanding Lewis dot chemistry. This article will show you the steps needed to draw any molecule’s Lewis dot structure.

Difficulty: Moderate

Instructions

Step 1

The first thing you need to do is learn and understand the periodic table. For example, you should know that hydrogen has one valence electron, carbon has four valence electrons, oxygen has six valence electrons, ect. The reason you must know this is because it’s the valence electrons that are used for bonding. The “dots” in a Lewis dot diagrams are the valence electrons. This of course is a very simplistic view of electrons as they are actually just energy. But it works as a good visual picture.
Step 2

It is best to start off with simple molecules and work your way up to harder ones. In this article, I will start with water. Water contains two hydrogen atoms and one oxygen atom. If you draw out the electronic configurations of both hydrogen and oxygen, you can see the valence (bonding) electrons more clearly. The picture to the left shows the configurations of both elements. As you can see, the two hydrogen’s have a total of two electrons available for bonding and oxygen has two electrons available for bonding (2Py and 2Pz). So, if you put two and two together you get water!
Step 3

Now you need to draw the Lewis diagram of water. Use can use dots or lines to represent electrons. I will use dots in this article. The diagram to the left shows the steps taken to draw a water molecule. First you draw one hydrogen atom with a dot. Next, you draw one oxygen atom with two pairs of electrons (4 dots total) and two separate electrons (2 separate dots). Finally draw your final hydrogen atom with one dot. Connect all three atoms together in the lowest energy configuration. For water, that would be bent. As you can see by the picture, the octet rule is in effect as well. There are a total of eight electrons around oxygen which is the maximum. The octet rule doesn’t always apply but is good rule in general chemistry.
Step 4

You can now draw the Lewis dot structure of a more complex molecule. Let us draw the Lewis dot of Acetone. This molecule is normally used as a solvent and is very good as a paint thinner and nail polish remover. Acetone contains three carbon atoms, one oxygen atom, and six hydrogen atoms (see picture). Again we can draw the electron configuration of carbon, oxygen, and hydrogen to see the electrons available for bonding. The configuration of carbon shows that there are a total of 12 electrons available for bonding (4 electrons*3 carbon atoms = 12). There are two available for oxygen and a total of 6 electrons available for hydrogen (1 electrons*6 hydrogen atoms).
Step 5

Now draw the configuration by putting lines (electrons) around each atom and then combine them together to make Acetone.
Step 6

This is a quick overview of the process and I hope it helps!