Ss19a Lewis Dot Diagrams printable pdf download

Ss19a Lewis Dot Diagrams

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Skill Sheet 19-A

Dot Diagrams

You have learned that atoms are composed of protons, neutrons, and electrons. The electrons

occupy energy levels that surround the nucleus in the form of an “electron cloud”. The

electrons that are involved in forming chemical bonds are called valence electrons. Atoms can

have up to eight valence electrons. These electrons exist in the outermost region of the

electron cloud often called the “valence shell”.

The most stable atoms have eight valence electrons. When an atom has eight valence

electrons, it is said to have a complete octet. Atoms will gain or lose electrons in order to

complete their octet. In the process of gaining or losing electrons, atoms will form chemical

bonds with other atoms. The method we use to visually represent an atom's valence state is

dot diagram,

called a

and you will practice drawing these in the following exercise.

1. What is a Dot Diagram?

Dot diagrams are composed of two parts—the chemical symbol for the element and dots

surrounding the chemical symbol. Each dot represents one valence electron. If an

element, such as oxygen, has six valence electrons, then six dots will surround the

chemical symbol as shown to the right.

Boron has three valence electrons, so three dots surround the chemical symbol for boron as

shown to the right.

There can be up to eight dots around a symbol, depending on the number of valence

electrons the atom has. The first four dots are single, and then as more dots are added,

they fill in as pairs.

2. Drawing Dot Diagrams

Using a periodic table, complete the following chart. With this information, draw a dot diagram

for each element in the chart. Remember, only the valence electrons are represented in the

diagram, not the total number of electrons.

Element

Chemical

Total Number of

Number of

Dot Diagram

Symbol

Electrons

Valence Electrons

Potassium

Nitrogen

Carbon

Beryllium

Neon

Sulfur

Ss19a Lewis Dot Diagrams