Summary

In this activity, students will use an online interactive to investigate the size of an atom, and compare the size of the atom to other objects using scientific notation.

Grade Level

Middle School, High School

NGSS Alignment

This activity will help prepare your students to meet the following scientific and engineering practices:

• Scientific and Engineering Practices:
  • Using Mathematics and Computational Thinking
  • Developing and Using Models

Objectives

By the end of this activity, students should be able to:

• Compare the size of an atom (qualitatively) to other objects
• Compare the size of an atom (quantitatively) to other objects, using scientific notation

Chemistry Topics

This activity supports students’ understanding of:

• Atomic structure
• Atomic scale
• Atomic radius
• Measurement
• Scientific notation

Time

Teacher Preparation: 15 minutes
Lesson: 45 minutes

Materials

• Device with internet access (phones will work, but larger screen is preferred); http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html
• Whiteboards for each group (3-4 students per group) and dry erase markers (large paper may be substituted if whiteboards are not available)
• Student handout

Safety

• No specific safety precautions need to be observed for this activity.

Teacher Notes

• I use this activity to help students build fundamental understanding about atoms and atomic structure at the beginning of the school year.
• Typically, I begin with the “Golden Penny” lab (can we actually coat a penny with gold?) which provides us with a starting point for our discussions on atoms. (This experiment can be found as part of The Captivating Chemistry of Coins lesson plan.) After we have established, as a class, that gold is made of only gold atoms, we begin to have conversations about exactly what atoms are, and start with a basic definition that atoms are the smallest piece of matter that still retains the properties of the element.
• Students have most likely used exponents and scientific notation in their math classes, but they may need a refresher, and many have not had to use exponents outside of a math classroom. As they will be using scientific notation many times in chemistry, this is a good time to review it and establish how it is used in the context of chemistry. If you feel your students would benefit from reviewing it in more detail before completing this activity, you could use this Scientific Notation activity first to review writing numbers in scientific notation, and/or this lesson plan on Using Scientific Notation in Chemistry. These would be particularly useful for the “Challenge Questions” at the end, which require them to put numbers into scientific notation and do calculations with them.
• The first guiding question for the students will be: “If we could split a piece of gold into smaller and smaller pieces, how small could we get - and have it still be gold?” Start this activity with a class discussion about this first question. Most students know that an atom is the correct answer, but do not know how small an atom actually is.
• Have students break into small groups to discuss the question “how small is an atom,” and make a prediction on their whiteboards. This is outlined in step 1 of the student instructions. Call on groups to provide their predictions, and post them somewhere in the classroom for later. They may not be able to express these in scientific notation yet, just fractions, and this would be a good time to introduce turning these into scientific notations. (Ex: if a student predicts that an atom is 1/1 millionth of a meter, show them how to write this as 1.0 x 10^–6)
• Although there may be some students who already have a good idea of just how small an atom is, many students struggle when trying to compare an atom to other objects. (Many students could not correctly compare an atom to a grain of sand.) This is outlined in step 2 of the student instructions. After each group predicts the placement of each item on their whiteboards (smaller than an atom of gold, larger than an atom of gold) allow them to work with the interactive before reviewing answers as a class. This is outlined in step 3 of the student instructions. The website can be accessed on most devices (phones/ipads/tablets) however, it is best viewed on a larger screen.
• Another similar resource that has even more examples with more in-depth explanations over a larger range of sizes (from 10^–35 m to 10⁺²⁷ m) can be found at The Scale of the Universe - and it was created by high school students! This could be a fun website to explore after completing this activity, and as all of the objects from the list in step 2 are specifically referenced in this program, it could be used for students to check their predictions.
• Students will continue to work in their small groups to answer questions using scientific notation and the interactive. After each group has answered questions 7-12, review the answers together as a class.
  • For these questions at the end of the activity, students’ answers should be reported with positive exponents based on the way the questions are phrased. Something would be 10² times (100 times) bigger or smaller, but you would never say something is 10^–2 times (0.01 times) bigger or smaller. The direction of the comparison is indicated by the phrases “how many times bigger” vs. “how many times smaller” rather than the +/– sign of the exponent.