UNIT 3 DAY 4 Covalent Bonds

Do Now/Catalyst (8 min) Take out your notes packet from Unit 3. Answer the following questions on a separate sheet of paper. 1. Write the chemical formula for the ionic compound that will form and then draw the electron transfer diagrams  Li and O

Do Now/Catalyst: Check Answers (2 min) 1. Write the chemical formula for the ionic compound will form with the following elements and then draw the electron transfer diagrams  Li and O = Li 2 O

How are you doing?

Introduction (5 min) Entrance Slip: Write your name and period at the top. If you did not do Day 2 or Day 3 Questions, do those now Answer the questions under Day 4. You may use your notes. SHOW:  Ion charges for K and O (1pt)  Chemical formula (cross over charges) (1pt)  Complete Electron Transfer Diagram (2pt)

Announcements Lab fees Behavior grade every two weeks ACT tutoring Sat 9am-12pm Office hours: Monday, Wednesday and Friday New homework policy – NO late work accepted BRING YOUR NOTES PACKET EVERYDAY! Homework DueExam Unit 3 Friday 11/9 ODDWednesday 11/14 ODD Tuesday 11/13 EVENThursday 11/15 EVEN

Objectives SWBAT explain the formation of covalent bonds. SWBAT draw Lewis Structures to represent the formation of covalent compounds.

REAL WORLD!! Gasoline is made of C-H bonds…which are covalent bonds!!

Covalent Bonds In Covalent Bonds, electrons are shared. Covalent bonds form between non-metals because of similarities in electronegativity. To depict the formation of covalent bonds, we use Lewis structures.

Lewis Structures In Lewis structures, we show a bond using line. Each bond represents two electrons. Bonds can be either single (one line), double (two lines), or triple three lines). To show lone electrons (those that are not shared), we draw dots.

Steps for drawing a Lewis Structure 1. Write out the number of valence electrons for each atom in the compound. 2. Multiply this number by the number of atoms of that element in the compound. 3. Add up all the valence electrons.

Steps for drawing a Lewis Structure 4. Determine how many electrons would be needed for each atom in the compound to have an octet. o Multiply the number of atoms by 8, except for H and He, which should be multiplied by two. 5. Compare the answer to Step 3 to the answer to Step 4. If the numbers don’t match, subtract, then divide your answer by two. This is the number of bonds you will need to draw.

Steps for drawing a Lewis Structure 6. Write the symbol of the least electronegative atom in the middle, and all other atoms around it. Draw one bond to each atom. 7. If you have bonds left over, draw more between the central atom and the other atoms. 8. When you’ve used all the bonds, draw dots around the other atoms until each has an octet. Remember to count each bond as two electrons.

Lewis Structure: CO 2 Draw the Lewis structure for CO 2 :

PRACTICE TIME!! Grab Whiteboard, an eraser, and a dry erase marker

We Do: Whiteboard Practice Problems Draw a Lewis structure for the following compound (copy into your notes): SiO 2

We Do: Whiteboard Practice Problems Draw a Lewis structures for the following compound (copy into your notes): CCl 4

We Do: Whiteboard Practice Problems Draw a Lewis structure for the following compound (copy into your notes): H 2 O

We Do: Whiteboard Practice Problems Draw a Lewis structure for the following compound: HCN

We Do: Whiteboard Practice Problems Draw a Lewis structure for the following compound: HF

We Do: Whiteboard Practice Problems Draw a Lewis structure for the following compound: NH 3

We Do: Whiteboard Practice Problems Draw a Lewis structure for the following compound: CH 4

You Do: Independent Practice Problems Answer the following book problems AND draw Lewis structures for each problem: P. 229 #7, 8 P. 238 #11, 20 P. 253 #31, 35

Closing Essential Question: How and why do electrons move between atoms when covalent bonds are formed?