Los Angeles Charter Schools Science Partnership
Model-Based Inquiry Lesson Plan
Lesson Title: Chemical Bonds
Topic/ Focus Area: Covalent and Ionic Bonding
Grade 8
Major Concept of Lesson: Covalent and ionic bonds are two major types of chemical bonds. Covalent
bonding involves the sharing of electrons between atoms. Ionic bonding involves the transfer of electrons from
one atom to another, thereby creating ions that attract each other.
Model: How will students demonstrate their understanding of the major concept?
Ss will be able to create diagrammatic and 3D physical models of molecular compounds. To build student
knowledge prior to this task, Ss will work with various models of atoms and molecules throughout the lesson.
These include Lewis dot structures, ball and stick, space filling models, analogies, illustrations, and animations.
Ss will also engage in evaluating their peers’ 3D models.
California Standard(s) to be addressed:
8.3.b. compounds are formed by combining two or more different elements. Compounds have properties that
are different from the constituent elements.
8.3.c. atoms and molecules form solids by building up repeating patterns such as the crystal structure of NaCl or
long chain polymers.
Student Objectives:
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SWBAT model how ionic bonds form.
SWBAT model how covalent bonds form.
SWBAT use information in the periodic table and knowledge of valence electrons, the octet rule, and
metals/nonmetals to determine whether atoms in an assigned molecule are covalently or ionically
bonded. They will then build a 3D model of the entire molecule based on this information.
SWBAT draw an accurate diagrammatic Lewis dot model of a carbon dioxide molecule, showing the
double bond.
Materials and Resources:
1. Article for Explain 1
2. For the 3D model building the suggested materials are: gum drops, pipe cleaners, toothpicks, modeling clay,
straws, bottle tops, glue, beads, popsicle sticks, foil, Skittles, yarn, coffee stirrers, paint, cotton balls.
3. Index Cards showing empirical formulas of ionic and covalent compounds- Prepare 1-2 cards of each kind of
bond for each group. For example: CH4, O2, N2, NH3, LiN2, NaCl, Cl2, MgI. Index card should show only the
empirical formula.
4. Power Point “Chembonds” by Charles Lemle
5. Optional: 3D Molecular Structuring Website: MathMol www.nyu.edu/pages/mathmol
Lesson Implementation Logistics:
1. Recommended Prior Instruction in: Review valence count; energy levels, periodic table atomic number and
its relationship to valence electrons, location of metals and nonmetals, Lewis dot diagrams
2. Lesson following: Metallic bonding, chemical reactions using compounds from the present lesson. (Teacher
will choose ones that will actually combine.)
3. For each group, prepare compartmentalized trays (e.g. egg cartons) with materials and index cards with
molecule assignments. This will cut down on time used for distributing materials.
4. Caution students not to eat candy.
Vocabulary:
ionic bonds, ionic charge, ionic compound, covalent bonds, covalent compounds, single bond, double bonds,
triple bonds, octet, octet rule, valence, valence electrons, polar, nonpolar covalent, polar covalent bond
Steps of the Lesson
Learning Activities which lead to
Model:
Inquiry-Based; ELL and or Literacy
Strategies; Scaffolding
Teacher Questions for
Activity:
Key questions that show
progression from lower
to higher order thinking.
Anticipated Student
Responses, Questions
and Errors:
ENGAGE
Warm Up
See Handout “Determining Accurate
Models-Lewis Dot Structures”
Display three elements and three
possible variations of those elements:
N, O, K, Mg, Cl, Na
Have students select the correct Lewis
T: This is a review warm
up. Which of the Lewis
dot structures is correct?
Why is it the correct one?
To encourage thinking, have
Ss do warm up without use of
book.
Teacher Response
to Students and
Teacher
Intervention
Activities or
Strategies
T can monitor to
assist Ss who need
review on filling in
energy levels.
When Ss have
completed the
warm up, have
them share. Ask
dot model that represents each Do not use your
element.
textbook.
Students should also explain why their
selection is correct and why the other
models are not correct.
EXPLAIN 1
(Pre-requisite Homework) Here Ss are
first introduced to bonding.
Students will read a selected text
(article or handout) about ionic and
covalent bonding). Students will
develop Cornell Notes from the
reading to develop essential questions
about molecular bonding.
In Class
1. Ss will share essential questions 1. What questions did
from their notes.
you have? What was
understandable? What
2. Pre-assessment-Our Initial Model
Prompt: “Draw a model of a carbon was confusing? How
dioxide molecule.” See handout “Pre- were the figures and
assessment/First Draft” slip for this.
diagrams helpful?
EXPLAIN 2
Power Point on Bonding
1. Power Point Introduction
T will use PowerPoint to explain why
atoms gain, lose, or share electrons, as
well as ionic and covalent Lewis
structures, and types of models.
T can also use the following analogies
to further clarify ionic and covalent
b. What is a nonpolar
bonds.
covalent bond? How do
a. Ionic: Pennies at 7 Eleven. they share the electrons?
“Sometimes
we
give, This idea might be
counterintuitive to Ss.
sometimes we get.”
b. Covalent:
Video
game
purchase between two friends
Nonpolar covalent bond-Share
the video equally. That is, if
both persons paid half the cost
of video game, each plays an
equal amount of time.
Polar covalent-Share non-
S: What are the dots?
“Why do you think
this?”
(Dots represent the valence
electrons.)
As Ss share Cornell
notes, note
questions Ss ask
and how they
answered them.
What was
particularly
difficult? Were
they able to capture
main ideas in
summary?
equally! That is, if one person
paid more for the video game,
he/she will get more time to
play.
2. Worksheet Practice
Ss will practice with manipulation of
electron dots to make ionic and
molecular compounds.
c. T: How can you
represent “sharing
electrons” and
3. Students create and write analogies
“transferring
(models) to explain covalent and ionic
electrons?” You saw
bonds.
some analogies in the
Students will pair-share and revise if
power point—the big
necessary.
and small dogs with
the bone. What are
some of your own
ideas?
EXPLORE
Build It!
Using a variety of materials provided
by the teacher, S groups will build
models of molecular compounds,
showing the correct type of bond.
(Index card assignments: CH4, O2, N2,
NH3, LiN2, NaCl, Cl2, MgI, etc.)
Procedure:
1. Teacher reviews and demonstrates
the 3 types of models, using materials
to give Ss ideas and examples. The 3
types are: ball and stick, Lewis dot,
and space-filling model. Point out that
each different kind of element should
be a different color.
2. Review “Steps to help Ss prepare
the 3D model” (see column 2).
3. Student groups work together to
build models. When they complete
model for one index card, teacher
gives them the next one. Ss should
build at least one ionic and one
covalent molecule.
4.
Place
completed
models
in
1. T: For example, we
can use 2 balls of clay to
represent two H atoms. A
toothpick can be used for
the bond that holds them
together. (Check that Ss
do not spell out names of
the elements with the
materials.
2. Steps to help Ss
prepare the 3D model:
a) Use the periodic table
to find out if molecule is
metal/nonmetal or
nonmetal/nonmetal, and
determine if bonds are
most likely ionic or
covalent.
b) Use periodic table to
draw the Lewis Dot
structure of each atom.
c) Move dots (electrons)
so octet rule is followed.
d) Use different colors
for electrons from
different atoms.
e) Build the 3D model
based on your drawing.
c. Monitor and
evaluate
discussions and
ideas of model as
Ss discuss and
write down the Pair
Share
Activity.
S: Does metal/nonmetal
have an ionic or covalent
bond? (ionic) Why do they
have ionic bond? What
does ionic mean?
T: If you look at
valence electrons
of metals, they
have a just a few.
It’s easier to give
them away than to
acquire a lot of
electrons from
another atom.
designated area for Galley Walk.
EXPLAIN 3
A. Student Explanation
1. Gallery Walk
Ss will examine a model from another
group and compare it to their own.
Each S will use the + and * format on a
card to write their thoughts.
2. Student groups share out gallery
walk findings with whole class.
Teacher monitors information shared
and clarifies or corrects any
misconceptions.
B. Teacher Explanation
For added practice and explanation,
teacher selects 2-3 molecules to work
out together with class. Again, follow
“Steps to Prepare a 3D model...”
ELABORATE
Empirical vs Ball and Stick Models
Ss will compare these two different
models of carbon dioxide. Students
will use a Venn diagram to compare
empirical formula model of CO2 with
the ball and stick model showing the
double bonds.
S: What will they look for
1. T: On the + side of
your card, write what you in our model when they
examine it?
like about the model, its
good and clear features.
On the * side, write any
suggestions you might
have to improve the
model, or what is not
clear about the model. At
the bottom of your card,
write how this model was
different from you own.
2. How was the model
you examined from the
other group different
from your own? How
was it similar?
1. What does the first
(formula) model show
that the second (ball and
stick) model does not
show? What does the
second show that the first
model does not show?
What do they have in
common?
S: Do the extra pairs of
electrons on the oxygen
just hang there?
T: What do you
think they should
look for?
Ss might suggest:
Show the correct
number of each
kind of element,
show the correct
number of
valence electrons.
Use arrows to
show movement of
electrons, lines to
show bonds
(single, double).
Label all parts of
the model!
2. Be sure Ss
share suggestions
in a constructive
way.
1. An empirical formula
gives the proportions of the
elements present in a
compound, but not the
arrangement of the atoms as
in a ball and stick model.
S: Do all molecules really
have 3D shapes to them?
(Yes, there are websites
with 3D models to help you
better visualize what they
might look like. See
MathMol website.
Also, colors are used to
distinguish atoms, but we
really don’t know the actual
colors.
Yes the extra pairs of
electrons on the oxygen
stay there. They are paired.
If you count the total
number of electrons around
oxygen, you will find that
there are 8, which follows
the octet rule. The same for
the number of electrons
around carbon.
EVALUATE
Post-Assessment:
Same as pre-assessment: Draw a
model of CO2.
Remind Students:
a. Be accurate in showing the
number of each kind of
element.
b. Be accurate in showing the
number of valence electrons.
c. Use arrows to show movement
of electrons, lines to show
bonds (single, double).
d. Label all parts of the carbon
dioxide model!
A common mistake to Ss
is to draw 2 carbon
atoms and 1 oxygen
atom. Remind them to
look carefully at the
formula!
Ss can draw their
model in two
parts. The first
part showing the
movement of
electrons, and the
second part
showing the
model again as a
ball and stick
model. It might
be too confusing
to read all the
information in a
single drawing.