Lesson Plan
Teacher: N’Djamina Johnson
Course: Chemistry
Unit 4 - Chapter 9: Covalent Bonding
Lesson: “Lewis Dot Structures”
Date: March 19-20, 2007
1. Initial Planning:
Classroom Context: I teach mostly sophomores and juniors. However, I do have few 12 th grade students who have failed Chemistry previously. I only have one EC (Exceptional Children) student, who is in my second period class. His only accommodation is extended time on exams and quizzes. I did this lesson with my first, second and third period; however, in my response I will focus on third period. My first period has 21 students, second has 14 students, and third period has 16 students.
Student Learning Objectives
Students will be able to:
1) Define covalent bond, bond dissociation energy, molecule, octet rule
2) Compare and contrast single, double, and triple bonds in terms of bond strength, bond length, and bond dissociation energy.
3) Compare and contrast sigma and pi bonds
4) Draw Lewis Dot structures for covalently bonded compounds
5) Use formal charge to ensure the correct charge on compounds
Science NCSCOS Objectives
Science NCSCOS Goal: 2.07 Assess covalent bonding in molecular compounds as related to molecular geometry and chemical and physical properties (Molecular 2.071)
Prerequisites:
Students are expected to know:
 The number of valence electrons in any element
 How to draw Lewis Dot Diagrams for any element
 The octet rule (need to have 8 electrons in the valence shell to be stable – 2 is okay if it is a small atom)
Resources needed (and different learning styles they meet)
 overhead projector
 overhead transparencies and markers (writing & visual & auditory – when I explain & students repeat & answer quesitons)
 whiteboard and whiteboard markers (visual & auditory & writing)
 Lewis Electron Dot Models Sets (10 sets) & overhead set for me (visual, kinesthetic)
 Lewis Electron Dot Modes Worksheet (50 copies) (writing activity)
2. Day 1: Lesson Introduction
Catalyst (Warm-up)

20 minutes
As the students enter the room, they must write down the agenda and the catalyst. Then they must begin working on the catalyst questions.
Agenda
I. Catalyst
*How do you find the number of valence electrons in Group A elements?
*How do you find the number of valence electrons in Group B elements?
*What is the octet rule?
*Draw the Lewis Dot Structure for Li, Zn, C, F
II. Covalent Bonding
III. Lewis Dot Structures & Formal Charge
IV. Lewis Electron Dot Models
To begin the class (after 15 minutes), I’ll ask students about their weekend, and if they have any fun stories to tell. After about 2 minutes, I’ll say “Let’s get started.” They know that’s the cue for when I will ask for a volunteer to read the student objectives (which are always written on the white board). Students earn
Scholar Points for participating in class, so each student who answers questions, volunteers for different activities will earn points. Then another volunteer will read the agenda for the day. I will then ask for volunteers to write the answers to the last question on the board, while we review the answers to the first three questions.
3. Lesson Development
Teacher Input
Covalent Bonding (20 minutes)
Students will copy the notes written below from the overhead as I explain them. Several times throughout the lecture, students will repeat important phrases. The notes are in blue, things I say are italicized. There are some CFU questions in my italicized words.
Covalent Bonding
*Covalent Bond: force that holds to atoms together in which the valence electrons are SHARED
Everyone say SHARED. louder, I can’t hear you, one more time.
What happens to the electrons in an ionic bond? (transferred)
*Molecule: the smallest unit of a covalently bonded compound.
*Bond Dissociation Energy (BDE): energy needed to break a covalent bond
*sigma bond: bond formed by the direct overlap of two atomic orbitals (picture)
*pi bond: bond formed by the overlap of parallel atomic orbitals (picture)
What does the symbol pi look like? How many electrons do you think Triple Bonds might share? Do you think it would be easier to break 1 broomstick, 2 broomsticks, or 3 broomsticks? So do single, double or triple have the most bond strength? What is BDE again? In that case, who has the highest BDE?
Single Bonds
 2 electrons shared
 1 sigma bond
Double Bonds
 4 electrons shared
 1 sigma, 1 pi
Triple Bonds
 6 electrons shared
 1 sigma, 2 pi bonds
 longest Bond Length
 least Bond Strength
 lowest BDE
 mid BL
 mid Bond Strength
 mid BDE
 shortest BL
 most Bond Strength
 highest BDE

I’ll tell them to stand up and ask two different people questions about the notes that we just wrote down, and then sit down again. I’ll walk around and monitor the discussions. Then I’ll ask if there are any questions that they heard that were left unanswered.
More Teach Input/Modeling:
Lewis Dot Structures & Formal Charges (20 minutes)
In this part of the Input, we will be connecting the prerequisite knowledge covered in the catalyst with the new knowledge that we discussed with “Covalent Bonding” and applying it to drawing covalently bonded molecules (Lewis Dot Structures). I will write the steps to drawing Lewis Dot Structures on the white board
(which are listed below) as I write an example on the overhead. My first example that I use to explain the steps will be methane (CH
4
). I will ask students to read the steps as I demonstrate them on the overhead.
Drawing Lewis Dot Structures & Formal Charge
1.
Draw Lewis Dot Structure for each element in your compound.
2.
Put least electronegative atom in the center (if carbon is present, ALWAYS put CARBON, NEVER
HYDROGEN).
3.
Arrange your atoms and their valence electrons around the central atom until each atom is surrounded by eight electrons (octet rule) unless it is a small atom, then 2 electrons is ok.
4.
Check formal charge of compound a.
Formal Charge = Valence e – e in lone pairs (unbonded e ) – ½ bonding e b.
(FC = zero for neutral compound, ions FC = charge on ion)
CFU Questions:
 Since Hydrogen is less electronegative than Carbon, I must put Hydrogen in the middle right?
 Why do I need to put eight electrons around Carbon?
 Why don’t I have eight electrons around Hydrogen?
 This Carbon is sharing 2 electrons with Hydrogen, so what kind of bond must it be?
 Does it have sigma, pi or both bonds?
4. Lesson Implementation
Guided Practice (10 minutes)
Lewis Electron Dot Models
When I explain the next example, I will send my students to the lab tables with lab partners and a Lewis Dot
Models Set & Worksheet. I will give them 1 minute to be at their table with their supplies. The first, second, and third table ready earns extra scholar points.
I will use my overhead set of the Lewis Dot Models to guide them through another example on the overhead. I will use water because it has lone pairs (non-bonding electrons). I will ask different students to read different steps, and do them on the overhead while students do them at their lab tables also.
Throughout the example, I will ask what I should do next, and ask students for answers instead of just showing them. I will guide them through filling out their worksheet that goes with the activity also. The final example will be with O
2
because it has lone pairs and a double bond. Again, I will show them how to do it on the overhead and while they are doing it with their lab partner at their table, and writing the answers on their worksheet.

I know that students who already understand the material will work ahead of me in front of the class, but that is why I want all students to be at the lab table. Students who need more examples can follow along, but students who understand can keep working.
I will ask if there is anything that is unclear about the activity or the instructions, and then let them continue on their own.
Independent Practice (15 minutes)
Students will continue to work on the Lewis Dot Models Set & Worksheet (which is scaffolded from easy to challenging), while I walk around the room to answer individual questions. There are 40 problems on the worksheet, so they will not finish on Day 1.
Closure (5 minutes)
I will give the students two minutes to finish the problem on which they are working, clean up their model set and return to their sets. First five people in their seats will earn scholar points. I will then pass out a covalent bonding worksheet that will help them practice drawing Lewis Dot Structures. Their “ticket out the door” will be to draw the molecule listed as #1 on the paper, tell how many electrons are shared. Their homework will be to finish the worksheet.
Homework: finish Covalent Bonding Worksheet.
Day 2:
Lesson Introduction (20 min)
Students are to turn in their homework when they come into the room, write their agenda, and start their catalyst.
I. Catalyst
*Write the formula for phosphate and carbonate.
*Draw the Lewis Dot Structure for the following molecules: NH
3
and CO
2
(use formal charge to check your answers)
II. Polyatomic Ions
III. Lewis Electron Dot Models
IV. Covalent Bonding Worksheet.
I’ll begin class after 15 minutes, and ask students to read the objectives (same as yesterday) and the agenda. I will ask students to for the answers to the catalyst questions. Hydrogen only shares two electrons, Carbon dioxide has a double bond and lone pairs on oxygen. Therefore I will follow up with questions like these:
 Why is Hydrogen only sharing 2 electrons?
 What are these electrons called out here (pointing to lone pairs)?
 Who has stronger bonds? Who has longer bonds?
 Why does the bond between Carbon Dioxide and Oxygen have a higher BDE than Hydrogen?
Lesson Development
Teacher Input
Polyatomic Ions (20 minutes)
First I will ask who remembers the definition of a polyatomic ion. Then I’ll tell them that yesterday, we learned about drawing molecules, which all had a formal charge of zero. But remember the formal charge

is not always going to be zero, like with polyatomic ions. Then I’ll show on the whiteboard how to draw polyatomic ions with a few tips to jot down in their notes.
Tips for Polyatomic Ions
*Total number of electrons is most important (not who owns the electrons)
*add an electron for every negative charge, subtract and electron for every positive charge
Ex: NH
4+
(positive 1 charge, subtract 1 electron)
Modeling/CFU: I will stop and demonstrate how to draw ammonium using the steps from yesterday and these two tips. I will also demonstrate on the overhead with my overhead set of Lewis Dot Models. I will ask them for each step of the way.
Teacher Input
*For many (not all) polyatomic ions, the number of bonds to the central atom = number of valence electrons
Ex: CO
3-2
Carbon has 4 valence electrons
Lesson Implementation
Guided Practice (5 minutes): I will stop and give the kids 1 minute to get to their lab station with their lab partner and the Lewis Dot Models Set and Worksheet. I will then demonstrate how to draw carbonate using the steps from yesterday and this last tip. Again I will demonstrate on the overhead with my overhead set of Lewis Dot Models while they do the same example at their lab stations. I will go through this example more quickly, but still ask questions as I go.
Independent Practice (30 minutes)
They will continue working on the 40 problems that they started yesterday. Today, they will have time to get to the problems which include polyatomic ions, and cause them to do some more intense thinking than yesterday. I will walk around the classroom, answer questions, and ask questions. If one team gets an answer that another team is struggling with, I will ask the teams to help each other build the models.
For the teams who finish early, they can begin working on their closure assignment.
Closure (10 minutes)
When there are 10 minutes left, I will give the students two minutes to finish the problem that they are working on, put their model set away and return to their seats. First I will ask if there are any general questions about the quiz tomorrow. Then I will let them begin the closure assignment. They must have at least the first 2 questions answered before they leave. Closure assignment will be a guided reading through the section in the textbook (Section 9.1) about Covalent Bonding. This assignment reviews more of the theory of covalent bonding that was covered on day 1. Since most of the time in this part of the unit has been spent on drawing the molecules, I thought it might be a good idea to review some theory for homework.
Homework: Finish Covalent Bonding 9.1, Study for Covalent Bonding Quiz tomorrow
5. Lesson Evaluation
Students will take a Quiz on Day 3 testing the objectives covered on Day 1 and Day 2. The quiz is broken up by objectives covered so that I can evaluate the students’ mastery on every objective. The quiz is on the page that follows.

% Mastery
% Mastery
% Mastery
Name: ___________________________________ Date: __________________ Period: ________
Quiz 4.2 Version 1
SWBAT define covalent bond, molecule, octet rule, bond dissociation energy
1.
Define the following terms: a.
covalent bond b.
bond dissociation energy c.
octet rule
SWBAT compare and contrast sigma and pi bonds
2.
What is the difference between a sigma bond and a pi bond?
Directions: Identify which of the following bonds contain sigma, pi or both bonds.
3.
Single sigma pi both
4.
Double sigma pi both
5.
Triple sigma pi both
SWBAT Compare and contrast single, double, and triple bonds in terms of bond strength, bond length, and bond dissociation energy.
Directions: Fill in the blanks with “single bonds”, “double bonds” or “triple bonds”
6.
Bond Length
__________________
Mid Length
________________
Shortest
____________________
Longest
7.
Bond Strength
____________________
Weakest
__________________
Mid Strength
________________
Strongest
8.
Bond Dissociation Energy
____________________
Most BDE
__________________
Mid BDE
________________
Lest BDE

% Mastery
SWBAT draw Lewis diagrams using formal charges
Directions: Indicate covalent bonding via drawing of Lewis structure (electron dot). You may use bond lines or all dots to connect each atom. All lone pairs should be indicated as ONLY dots written darkly and clearly enough for the teacher to be able to interpret them. Check your answer using formal charges
9.
CCl
4
10.
O
2
11.
NH
3
12.
CHCl
3
13.
CO
32-
14.
PO
43-

6. Lesson Reflection
Here are the results for each objective for each period.
Average Mastery per Period, per Objective
Period 1
Period 2
Obj 1 vocab Obj 2 sdt bond Obj 3 σ/  bond Obj 4 Lew. Dot Averages
94
93
91
89
95
100
70
72
88
89
Period 3
Overall
Average
96
94
83
88
86
94
77
73
86
88
After the lesson, I thought that it may have been better to find a way to break up the 40 minutes of Teacher
Input on Day 1. I could have had some quick rotating stations with pictures of molecules with single, double, and triple bonds. Then at each station I could have asked questions about the pi and sigma bonds, number of electrons shared, etc. I think that it may have been a better way to get my kinesthetic learners moving a little bit more on day 1, and perhaps still that covalent bonding theory in their heads a little bit more. However, based on the class averages, they did not seem to need extra practice with it anyways.
I also think that they could have used some more practice with drawing covalent molecules. That was the weak point in all three classes with an overall average of 73%. A lot of my students still seemed quite confused about when and why to form double and triple bonds. So, perhaps if I made this a 3 day lesson, with the quiz on a Day 4 they would have understood the formation of multiple bonds with Lewis Dot
Structures a little better. Then I could have scaffolded the bonding by sticking to single bonds on day 1, adding double and triple bonds on day 2, and then adding polyatomic ions on day 3 before testing them on day 4.
7. Student Writing & Conventions
My students do not write many sentences or paragraphs in this lesson due to the nature of the lesson. So,
I do not have much mechanics, grammar or usage to check with my students. However, in my notes that I give to my students, I use correct mechanics and grammar unless I’m giving them shorthand notes.