11/4 what are lewis structures? - part ii
TRANSCRIPT
Launch: 11/4 Grab your binder and immediately take a seat!
Place homework (practice questions) on desk
1. Draw the correct Lewis structures for the following atoms. Be sure to use the 3-steps!
i. Br2
ii. H2S iii. CCl4
Schedule We have an exam in 6 days!
We don’t have time to waste! Follow our 7 class rules
You may not use inappropriate language
If you have a question, ask!
What are Lewis structures? – Part II
Mr. Heffner 11/4/09
Lewis structures are… pictures of covalent molecules
nonmetal and nonmetal share to get 8
F • • • • • • -
What are Lewis structures?
Lewis Structure
F • • • •
• • Covalent Bond
(dash = 2 electrons)
8 =
What are Lewis structures?
Cocaine C17H21NO4
Double Bond 2 dashes = 4 electrons
What are Lewis structures? Large biological molecules are made of
carbon (C) – 4 bonds nitrogen (N) – 3 bonds
oxygen (O) – 2 bonds hydrogen (H) – 1 bond
To fill octet C, N, & O sometimes form double/triple bonds H, I, Br, Cl and everything else = only single bonds
What is a Lewis structure? There is a 3-step process for creating Lewis
structures: 1. Draw Lewis symbols & count dots 2. Arrange atoms so they have a full octet
If necessary form a double/triple bond
3. Count dots & make bonds
Example Draw the Lewis structure for O2
Step 1: Draw Lewis symbols & count dots
O • • •
• • • 12 dots
O • •
• •
• •
Example Draw the Lewis structure for O2
Step 2: Arrange atoms so they have a full octet
7 = 7 =
O • • • • • • O
• •
• •
• •
Example Draw the Lewis structure for O2
Step 2: Arrange atoms so they have a full octet
8 = 8 =
O • • •
• • • O
• •
• •
• •
• •
• • •
Example Draw the Lewis structure for O2
Step 3: Count dots & make bonds
O • • • • • O •
• • •
Double Bond 2 dashes = 4 electrons 12 dots
Example Draw the Lewis structure for N2
Whiteboards Work in pairs
Trade-off marker every question
You have 60 seconds to draw the answer Show all three steps!
Lift board only when prompted
CCl4
CO2
CH2Cl2
N2
Molecular Models Work with partner
1. draw all the Lewis symbols 2. draw the correct Lewis structure
3. build a model using toothpicks and candy 4. draw a picture of your model (label the atoms) 5. identify the types of bonds present in molecule
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Step 1 Step 2 Step 3
Exit Slip 1. The bonds in water (H2O) are
a. single bonds b. ionic bonds
c. triple bonds d. double bonds
Exit Slip 2. The correct Lewis structure for CO2 is
Exit Slip 3. Which of the following molecules contains a
covalent triple bond? a. C2H2 b. I2 c. NH3
d. N2
Exit Slip 4. Bubble in A
Then, draw the Lewis structure for SiF4
Exit Slip 5. Bubble in A
Then, draw the Lewis symbol for O2
Homework Finish Lewis symbol and ions worksheet