Atoms and Molecules

Carrie Robatcek, Cold Spring Elementary, Cold Spring, Minnesota, based on an original activity from Janice VanCleave's 204 Sicky, Gloppy, Wacky & Wonderful Experiments, page 52.
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Summary

As part of the introduction to the Periodic Table of the Elements, students will be introduced to the idea of atoms, molecules, and chemical reactions. The physical manipulation of marshmallows (atoms) and toothpicks (bonds) will create a visual representation of the molecular structure of water. A second step requires students to create a second molecule using similar materials and using the Periodic Table as a reference point.

Learning Goals

Students will be able to display and describe the concept of an atom. (knowledge/comprehension)
Students will be able to display and describe the concept of a molecule and bonds. (knowledge/comprehension)
Students will use the Periodic Table of the Elements as a reference tool. (comprehension)
Students will create a second molecular model of their choice independently. (application)

Context for Use

Grade 6.
Full classroom instruction (30 students) is possible with table space to create models.

Lecture time is needed to explain Periodic Table of the Elements before these hands-on activities.

Atoms and molecules are not currently in our science curriculum, but I intend to incorporate them into our environmental studies unit. We work closely with our local watershed district and the DNR to provide environmental studies built around our local lakes and rivers.

Subject: Chemistry:General Chemistry:Bonding & Molecules, Atomic Structure, Elements & Periodic Table
Resource Type: Activities:Classroom Activity
Grade Level: Middle (6-8)

Description and Teaching Materials

Lesson 1 – Structured Practice

1) Distribute several bowls of colored marshmallows, both miniature and regular sized, to student work tables. Purchase mixed bags of pastel colored marshmallows (green, yellow, pink) and bags of white.
2) Distribute toothpicks to each table.
3) Distribute enough laminated copies of the Periodic Table of the Elements to have as references at each work table.
4) Create a key on the board with the students to define which color and size of marshmallow represents which atoms. {pink = carbon (C), small white = oxygen (O), large white = hydrogen (H), green = sodium (Na), green = chlorine (Cl), etc.}
5) Create a worksheet to have students record the any or all of the following:
a. draw the molecule representation on a piece of paper with colored pencils
b. label the atoms in the drawing
c. name the newly created molecule
d. list the number of each atom type
e. calculate the molecular weight using the Periodic Table of the Elements
6) Collect student worksheets to monitor accuracy before Lesson 2.
7) Assign students the task of coming to class the next day with a molecule that they would like to create. Have them search the Internet for the molecular structure of their choice.

Lesson 2 – Guided Practice / Independent

1) Repeat steps 1-3 from above.
2) Remove the key from the classroom that assigned atoms to marshmallow colors from the previous lesson. Allow students to rename marshmallow colors based on individual needs.
3) Ask students to follow the same steps used in Lesson 1 to create a model and again record their data on a worksheet used from the previous lesson

Teaching Notes and Tips

Depending on prior knowledge of the Periodic Table, you could tackle more concepts such as: chemical reaction, chemical change, reactants, products, and law of conservation of matter.

You could use buttons or clay to represent atoms, along with toothpicks or pipecleaners to represent bonds.

I have not done this activity yet in class, but have practiced at home. I actually had better luck with the model staying together when the marshmallows got harder.

Assessment

Lesson 1 activity worksheet will be recorded as a participation grade.
Lesson 2 activity worksheet and model will be recorded as a performance grade.

Standards

Grade 6, II. Physical Science, A.1-2-3, (matter is made up of small particles)

References and Resources