Chemical Reactions Live Class #2

​Making Lewis Dot Structures!

​​A Lewis structure, or a Lewis diagram, is a model that shows the valence electrons surrounding the symbol for an element. Lewis structures are useful models because they help show why and how elements form chemical bonds.

To draw a Lewis model, follow these steps.

1. Write the symbol of the element.

2. Find the number of valence electrons using the group number.

3. Place dots to represent valence electrons. Place 1 dot on each side of the symbol (above, right, below, and left) until no valence electrons remain.

4. If there are more than 4 valence electrons, create pairs with the remaining dots.

​​Follow these steps to use Lewis diagrams to model covalent bonding.

(Sharing of Valence Electrons)

1. Draw Lewis models of each element.

2. Identify the electrons that will pair up to share. Repeat until all electrons are paired.

3. Redraw the model as a full molecule.

Remember, we want to satisfy the octet rule for all elements in a covalent bond. Oxygen will need 8 valence electrons to satisfy the octet rule.

Hydrogen is the exception because it is in the first period on the periodic table. Hydrogen and Helium are the only elements on the periodic table that are happy when they have 2 valence electrons!

Remember, we want to satisfy the octet rule for all elements in a covalent bond. Nitrogen will need 8 valence electrons to satisfy the octet rule.

Chlorine will also need 8 valence electrons to satisfy the octet rule.

Nitrogen has 5 valence electrons so it will want to make 3 covalent bonds.

Chlorine has 7 valence electron so it will want to make 1 covalent bond.

Nitrogen will be our central element to build off of because it wants to make more bonds!

Remember, we want to satisfy the octet rule for all elements in a covalent bond. Fluorine will need 8 valence electrons to satisfy the octet rule.

Carbon will also need 8 valence electrons to satisfy the octet rule.

Carbon has 4 valence electrons so it will want to make 4 covalent bonds.

Fluorine has 7 valence electrons so it will want to make 1 covalent bond.

Carbon will be our central element to build off of because it wants to make more bonds!

Modeling Ionic Bonds (Stealing/Transfer of Valence Electrons)

Follow the steps below to use Lewis diagrams to model an ionic bond.

• Draw a Lewis structure of each element.

• Draw arrows to show the movement of the electrons.

• Draw the final structures of the ions.