Summary

In this lesson, students explore the structure of matter by designing, building, comparing, and evaluating models of a variety of simple molecules. In Part A, they explore differences in composition (types and ratios of atoms) between simple compounds. In Part B, they explore differences in structure. Students then use what they have learned to better understand how different substances are different and why they have different properties.

Grade Level

Elementary school

Standards

NGSS and Cross-Disciplinary Extensions addressed in this lesson

Objectives

By the end of this lesson, students should be able to

• Describe the building blocks of matter (atoms and molecules).
• Differentiate between an element and a compound.
• Identify two ways that substances can be different from each other at the molecular level (composition and structure).
• Identify relationships between the properties of a substance and its molecular composition and structure.

Chemistry Topics

This lesson supports students’ understanding of the following topics in chemistry:

• Matter
• Atoms
• Molecules
• Chemical bond

Time

Teacher Preparation: 15 minutes

Lesson: Part A: 60-75 minutes; Part B: 60 minutes

Materials

Part A

Prepared beforehand:

• Notecards (one for each group of 2-3 students), each with the name of one of the following substances: water, salt, or carbon dioxide
• Notecards (at least one for each group of 2-3 students), each with the name of one of the following substances: hydrogen peroxide, rubbing alcohol (isopropyl alcohol), oxygen gas, silica

For each group:

• Small cup with salt
• Small cup with water
• Small cup, empty
• Access to the Internet and other research materials
• Pens, pencils, crayons, paper

For the class: Groups will be able to choose which materials they would like to use to make their models.

• To model atoms: objects of various colors and sizes, such as
  • LEGOs
  • Candy, such as gumdrops, skittles, soft mints, hard candy
  • Marshmallows
  • Styrofoam balls
  • Cotton balls
  • Wooden spheres
  • Clay
• To connect atoms: materials such as
  • Toothpicks
  • Tape
  • Glue
  • Glue dots
  • Wood sticks
  • Sticky-backed Velcro
  • Clay

Part B

• Samples and/or photographs of graphite and diamond
• Images of the structure of graphite and diamond
• Gumdrops or marshmallows of different colors and sizes
• Toothpicks
• Narrow tube, such as a paper towel tube
• Board to use as a ramp
• Objects like wooden blocks to use as weights

Safety

Discourage students from eating any of the edible materials at any point before or after the lesson. Once materials are out of the containers and handled by students, they are no longer safe to eat.

Vocabulary Terms

• Atom
• Element
• Molecule
• Compound
• Property
• Model

Keywords

atom, molecule, element, compound, structure, model, matter, properties, mineral

Teacher Notes

Many students have difficulty envisioning what exactly matter is made of and what it looks like on a tiny scale. It is difficult to understand that everything around them is made of distinct microscopic parts (atoms and molecules). Whereas some have trouble believing that a visible droplet of water is made of trillions and trillions of tiny identical pieces of water, others have trouble believing that there is a physical limit to how small a “piece” of water can be and that it cannot be split apart forever.

This is really a basic lesson designed to get across three main points:

1. Substances are made of tiny parts called atoms and molecules.
2. One reason that substances are different from each other is because they are made of different numbers of different types of atoms.
3. Another reason substances are different from each other is because those atoms and molecules are arranged differently in different substances.

Download the Teacher Guide to view the rest of this lesson.