How to Draw Lewis Structures

What are Lewis Structures?

• Simplified Bohr diagrams which only consider electrons in outer energy levels.

• The Lewis structure consists of the element symbol surrounded by “dots” to represent the number of electrons in the outer energy level.

What is a valence electron?

• A valence electron is an electron in the outer shell of the atom.

• An electron in the outer shell of an atom that can be lost to or shared with another atom to form a molecule.

• Molecules will be discussed later when learning chemical reactions.

How are Lewis Structures and Bohr Models Alike?

• They both represent the number of electrons on the valence shell – the outer shell

• The Lewis structure is more simple than the Bohr model

How are Lewis Structures and Bohr Models Different?

• The Bohr model places electrons in energy levels (represented by rings) around the nucleus

• The Lewis structure places the electrons around the chemical symbol. The number of valence electrons is placed in a square design.

Lewis Structures

1) Find your element on the periodic table.2) Determine the number of electrons in the

last shell. This is called the valence shell3) This is how many electrons you will draw.

Lewis Structures

• Find out which group (column) your element is in.

• This will tell you the number of valence electrons your element has.

• You will only draw the valence electrons.

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Groups - Review

•Each column is called a “group”

•Each element in a group has the same number of electrons in their outer orbital, also known as “shells”.

Except for He, it has 2 electrons

•The electrons in the outer shell are called “valence electrons”www.chem4kids.com

Lewis Structures

1) Write the element symbol.

2) Carbon is in the 14th group, so it has 4 valence electrons.

3) Starting at the right, draw 4 electrons, or dots, counter-clockwise around the element symbol.

Lewis Structures

1) Check your work.2) Using your periodic

table, check that Carbon is in the 4th group.

3) You should have 4 total electrons, or dots, drawn in for Carbon.

Try these elements on your own:

a) Hb) Pc) Cad) Are) Clf) Al

Videos of Lewis Structures

• Bozeman science• Steps to Drawing Electron Dot Diagrams

Lewis Structures

On your paper, try these elements on your own:

a) Hb) Pc) Cad) Are) Clf) Al

Lewis Structures

On your worksheet, try these elements on your own:

a) Hb) Pc) Cad) Are) Clf) Al

Lewis Structures

On your worksheet, try these elements on your own:

a) Hb) Pc) Cad) Are) Clf) Al

Lewis Structures

On your worksheet, try these elements on your own:

a) Hb) Pc) Cad) Are) Clf) Al

Lewis Structures

On your worksheet, try these elements on your own:

a) Hb) Pc) Cad) Are) Clf) Al

Lewis Structures

On your worksheet, try these elements on your own:

a) Hb) Pc) Cad) Are) Clf) Al

Lewis Structures

On your worksheet, try these elements on your own:

a) Hb) Pc) Cad) Are) Clf) Al

Chemical Bonding

• Chemical Bonds Video Quiz

Video Answer Key