Welcome Silently 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

32 Announcements Today’s Homework:  Lewis Dot Structure Worksheet  Read Pages complete all activities USA TestPrep due on Monday Science Fair Presentations start on the 13 th  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.

17 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 O Oxygen Oxygen is in group 16 therefore O has 6 valence electrons. 8p+ 8n 16 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

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18 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 O Oxygen 16 O S Sulfur 16 S

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19 Lewis Dot Diagrams Unpaired valence electrons represent electrons available for bonding. O Unpaired Valence Electron H H O H

What does bonding look like? Page 400 Figure 3 Sodium Chloride (NaCl) Salt can dissolves in water. Water molecules eventually bond to all of the ions and the solid crystal will be completely dissolved. 12

20 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.

21 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.

22 Elements# of Valence Electrons Lewis dot diagram # of unpaired electrons 1. Lithium 2. Boron 3. Potassium 4. Chlorine 5. Nitrogen

23 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.

24 Elements# of Valence Electrons Lewis dot diagram # of unpaired electrons 1. Lithium 2. Boron 3. Potassium 4. Chlorine 5. Nitrogen 5

25 Example: Nitrogen Step 2: Write down the symbol of the element. The symbol of Nitrogen is N 7 Nitrogen 15 N

26 Elements# of Valence Electrons Lewis dot diagram # of unpaired electrons 1. Lithium 2. Boron 3. Potassium 4. Chlorine 5. Nitrogen 5 N

27 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 N N

28 Elements# of Valence Electrons Lewis dot diagram # of unpaired electrons 1. Lithium 2. Boron 3. Potassium 4. Chlorine 5. Nitrogen 5 N

29 Example: Nitrogen Step 4: Count the number of unpaired electrons. 7 Nitrogen 15 N N 3 Unpaired Electrons

30 Elements# of Valence Electrons Lewis dot diagram # of unpaired electrons 1. Lithium 2. Boron 3. Potassium 4. Chlorine 5. Nitrogen 5 N 3

31 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 Cl 7 1K Li1

32 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 Read and Complete all activities Remediation make up