WelcomeSilently Begin Do Now

1. Describe how the particles in a gas move.

2. Draw an Oxygen atom using Bohr’s Model.

3. A compound is:4. A bond is:

Particles move freely or independently

8p+

Two or more different elements combined

The force that holds elements together in a compound

8n

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Announcements

Today’s Homework: Lewis Dot Structure WorksheetRead Pages 359-363 complete all

activitiesUSA TestPrep due on MondayScience Fair Presentations start on the

13th

10 days left (Lab reports and power point presentations due)

Table of Contents: Lewis Dot Diagrams

L.O. SWBAT determine the number of bonds an element can make.

4

The Current Periodic Table Review• Elements are put in rows by increasing

ATOMIC NUMBER!!• The horizontal rows are called periods and are

labeled from 1 to 7.• The vertical columns are called groups and are

labeled from 1 to 18.

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Thinking Back

Valence Electrons :electrons in the outermost energy level from the nucleus.

The number of valence electrons an atom has corresponds to the group the atom lies in on the Periodic Table of Elements.

8

OOxygen

Oxygen is in group 16 therefore O has 6 valence electrons.

8p+8n

16

Valence electrons

Valence electrons

6

Groups…Here’s Where the Periodic Table Gets Useful!!

• Elements in the same group have similar chemical and physical properties!!

• (Mendeleev did that on purpose.)

Why??• They have the same

number of valence electrons.

• Exception He, WHY?

Turn to page 360• Fill in the boxes at the top of the page.• Helium is tricky! (Hint: determine the # of e-)

7

8

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Lewis Dot Diagrams

Lewis dot diagrams show valence electrons as dots placed around the element symbol.

Elements in the same group have the same Lewis dot structure.

8

OOxygen

16

O

16

SSulfur

16

S

10

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Lewis Dot Diagrams

Unpaired valence electrons represent electrons available for bonding.

OUnpaired Valence Electron H

H O H

What does bonding look like?

Page 400 Figure 3Sodium Chloride (NaCl)Salt can dissolves in water. Water molecules eventually

bond to all of the ions and the solid crystal will be completely dissolved.

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Importance

It is important to know how to draw Lewis dot diagrams because:

They are a fast and simple way to represent valence electrons.

They show the electrons available for bonding. They will be part of the FCAT.

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How to Draw Lewis Dot Diagrams

Step 1: Find the number of valence electrons.Step 2: Write down the element symbol.Step 3: Place a dot for each valence electron

on each side of the symbol with no side receiving two dots until each side receives one.

Step 4: Write down the number of unpaired electrons available for bonding.

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Elements # of Valence Electrons

Lewis dot diagram

# of unpaired electrons

1. Lithium

2. Boron

3. Potassium

4. Chlorine

5. Nitrogen

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Example: Nitrogen

Step 1: Find the number of valence electrons.

7

N

Nitrogen

15

Nitrogen is in Group 15 so there are 5 valence electrons.

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Elements # of Valence Electrons

Lewis dot diagram

# of unpaired electrons

1. Lithium

2. Boron

3. Potassium

4. Chlorine

5. Nitrogen 5

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Example: Nitrogen

Step 2: Write down the symbol of the element.

The symbol of Nitrogen is N7

Nitrogen

15

N

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Elements # of Valence Electrons

Lewis dot diagram

# of unpaired electrons

1. Lithium

2. Boron

3. Potassium

4. Chlorine

5. Nitrogen 5 N

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Example: Nitrogen

Step 3: Place a dot for each valence electron on each side of the symbol with no side receiving two dots until each side receives one.

7

Nitrogen

15

NN

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Elements # of Valence Electrons

Lewis dot diagram

# of unpaired electrons

1. Lithium

2. Boron

3. Potassium

4. Chlorine

5. Nitrogen 5 N

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Example: Nitrogen

Step 4: Count the number of unpaired electrons.

7

Nitrogen

15

N N 3 Unpaired Electrons

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Elements # of Valence Electrons

Lewis dot diagram

# of unpaired electrons

1. Lithium

2. Boron

3. Potassium

4. Chlorine

5. Nitrogen 5 N 3

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Elements # of Valence Electrons

Lewis dot diagram

# of unpaired electrons

1. Lithium

2. Boron

3. Potassium

4. Chlorine

5. Nitrogen 5 N 3

3 B

Cl7

1 K 1

3

1

1Li1

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Practice On Your Own

Write your summary (Exit Ticket 3-4 sentences) Today I learned how to ….. What are valence electrons? What are the steps you need to take to draw a

Lewis Dot Diagram.

Lewis Dot Diagram Worksheet – Fin? Have Ms. Ski check your work

Textbook pages 359-363 Read and Complete all activities

Remediation make up