Name: Date:

Student Exploration: Molecule Builder

Vocabulary: chemical bond, chemical formula, covalent bond, double covalent bond, cyclic
molecule, hydrocarbon, ionic bond, isomers, Lewis structure, molecule, organic compound

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

Look at the water molecule shown below. In the molecule, chemical bonds are shown as lines
between the atoms.

1. The red atom in the middle is oxygen. How many

bonds does the oxygen atom have?

2. The two white atoms are hydrogens. How many

bonds does one hydrogen atom have?

3. The chemical formula of water is H2O. In this formula, what do you think the “2” between
the H and O refers to?

Gizmo Warm-up
In the Molecule Builder Gizmo, drag an oxygen atom into the white
simulation area. The short blue lines extending from the atom represent
possible chemical bonds.

1. How many bonds can oxygen form?

2. Drag a hydrogen atom into the area. How many bonds can hydrogen form?

3. Drag the hydrogen atom on top of the oxygen atom. What happens?

The black line represents a chemical bond between the hydrogen and oxygen atoms.

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4. Bond another hydrogen atom to the other side of the oxygen atom. Now, enter the formula
“H2O” into the Type the formula below box. Congratulations! You have created a water
molecule. Select Show 3D structure to see what the molecule looks like in 3D.

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 Get the Gizmo ready:
Activity A:
 Check that the Free build mode is selected.
Simple molecules  If necessary, double-click on the trash can icon to
clear the simulation area.

Introduction: Not every group of bonded atoms is a molecule. In a molecule, the chemical
bonds connecting atoms are covalent bonds. In a covalent bond, bonded atoms share pairs of
electrons. (In an ionic bond, electrons are transferred from one atom to another.)

Question: What is the structure and chemical formula of simple molecules?

1. Explore: On your own, experiment by dragging different atoms into the simulation screen
and bond them together. When you have completed a molecule, try typing its formula into
the “Type formula” box. See if you can figure out how to write formulas for simple molecules.

When you enter the correct formula for a

molecule you built, it appears in the
Completed molecules area. Which
molecules have you completed so far?

2. List: Drag each element into the area. How many bonds can each element form?

Carbon: ___ Nitrogen: ___ Chlorine: ___ Sulfur: ___ Hydrogen: ___ Oxygen: ___

Which element forms the greatest number of bonds?

3. Create: Clear the simulation area, then drag two oxygen atoms into the area.

A. Create a bond between the two oxygen atoms. How many bonds does each atom

have remaining?

B. Click on the bond. What happens?

This is a double covalent bond. In this bond, two pairs of electrons are shared.

C. Enter the formula O2 into the box, then view the 3D molecule. Notice the subscript “2”
follows the element it describes, in this case oxygen.

4. Create: Clear the screen, then drag out two nitrogen atoms. Bond them together to form a

complete N2 molecule. What type of bond do you think you formed?

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 Enter the formula into the area, then view the 3D nitrogen gas molecule. Nitrogen molecules
contain triple bonds, so they share three pairs of electrons.

(Activity A continued on next page)

Activity A (continued from previous page)

5. Practice: Write the formula for each molecule shown below. Then, check your work by
creating the molecule in the Gizmo and writing the formula. (Don’t worry too much about the
order of elements in the formula for now.)

Formula: _____ Formula: _____ Formula: _____

6. Practice: Under Mode, select Build from formula. Check that Simple molecules are
selected. Turn on Show Lewis structure. A Lewis structure is a diagram that shows the
2D structure of the molecule.

Each time you complete a molecule, click Check. List the full name of each molecule below.
Select Show 3D structure to view what the molecule really looks like in three dimensions.

Cl2: O2: N2: H2O:

NH3: CO2: CH4: C3H8:

7. Extend: Molecules that contain C-H bonds are called organic compounds. Most organic
compounds are produced by living things. Look at the Lewis structure of the organic
compound propane, C3H8. Based on the structure of propane in the Gizmo, what do you
think is the structure of butane, C4H10? Draw a picture below, then see if you are correct
using the Free build mode of the Gizmo.

C4H10 Methane, propane, and butane are all

examples of hydrocarbons. As the
name implies, hydrocarbons are
made of hydrogen and carbon. Many
fuels are hydrocarbons.

8. Infer: Of the elements you can see in this Gizmo, which element would you choose to form
the inner structure, or “skeleton,” of a complicated molecule? Explain your choice.

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 Get the Gizmo ready:
Activity B:  Select Build from formula.
Cyclic molecules  Select Cyclic molecules and check that C3H6 is
selected. (If not, click the Prev. button.)

Goal: Build ring-shaped molecules.

1. Create: The challenge molecule should be C3H6. Drag three carbon atoms into the
simulation area, then bond them into a straight row. Be sure to use single bonds.

A. Click Make cyclic. What happens?

A cyclic molecule has a ring structure.

B. Complete the molecule using the hydrogen atoms. (Turn on Show Lewis structure
if necessary.) Click Check and Show 3D structure.

What is the name of the molecule you created?

2. Practice: Use the Lewis structures as a guide to complete the next three cyclic molecules.
List the name of each molecule you create.

C3H4: C5H8: S8:

Which molecule does not contain any carbon?

3. Challenge: Click Next and create the most complex molecule in the Gizmo, C6H12O6. Start
with a horizontal line that contains five carbons and one oxygen. Then click Make cyclic.

Use the Lewis structure to complete the molecule. (Note: In this structure, OH is shorthand
for a hydrogen atom connected to an oxygen, like O-H.) Click Check and Show 3D
structure when the molecule is complete.

What is the name of this molecule?

Glucose is a basic sugar used as an energy source by living things. Glucose molecules can
be linked together to form complex sugars and carbohydrates.

4. Think and discuss: Most of the molecules in living things contain rings of carbon and
oxygen. Why do you think carbon is such an important element in forming these molecules?

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 Get the Gizmo ready:
Extension activity:  Select Build from formula.
Isomers  Select Isomers. Check that the challenge molecule
is C4H6, or butyne.

Introduction: Sometimes compounds have the same chemical formula but different structures.
These alternate structures are called isomers.

Goal: Create multiple versions of the same compound.

1. Create: Check that the challenge molecule is C4H6, or butyne. Turn on Show Lewis
structure. Create the first isomer of butyne, click Check, and view the molecule in 3D.
Sketch the Lewis structure in the left box below.

Click the right arrow to see the Lewis structure of isomer 2. Build this molecule and click
Check, then sketch the Lewis structure in the right box. Circle at least one place where the
two isomers are different.
Butyne (isomer 1) Butyne (isomer 2)

2. Practice: Using the Lewis structures as a guide, create the remaining isomers. If you like,
you can take screenshots of the isomers you create and paste them below. (To do this, click
the camera icon ( ) and paste the resulting screenshot either into this document or into a
blank document to print out and turn in with this sheet.)

3. Go beyond: Allotropes are elements that have different

structures. For example, graphite and diamond are two
allotropes of pure carbon. You can see their crystal
structures at right.

A. Look carefully at the highlighted carbon atoms.

How many bonds does each form?

B. Diamonds are very hard, while graphite is the

soft black substance in a pencil lead. Based on
their structures, why do you think diamonds are
much harder than graphite?

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