blackboard with "the atom" written in chalk

Everything You Need to Know About How to Teach Atomic Structure

Reading Time: 3 minutes

Similar to our discussion of matter, many students come into the high school chemistry classroom knowing a little bit about atoms. 

I would encourage you to check out your state’s middle school science standards. You might be surprised to see how much chemistry is in there. For the most part, the chemistry they remember is more surface level. They know that atoms exist and that they are made up of protons, neutrons, and electrons. Our students may also know a little bit about ions. 

It’s our job to stretch that understanding. In this atom unit, I like to focus on how the atomic model has changed over time, laying the groundwork for their mental models changing throughout the year. 

Atomic Structure Lesson Plans

Total Duration: (10.5-14 days)

Note: a day refers to 45-50 minute periods.

Topic & TimelineTasksDescription
Introduction
0.5-1 day		Build-an-atom pHetI introduce my atom unit with the Build-an-atom pHet. Students get a chance to review subatomic particles as well as learn isotopic notation. 
How the model has changed
2-3 days		History of the Atom Project

History of the Atom Notes+Discussion		Students work in pairs or small groups to develop a short presentation about a specific atomic model. I have a large list of chemists/models to choose from. They are required to include: time period, country of origin, model of the atom, did their model confirms/contradicts the previous model, and was their model accepted at the time? I give them one day to research and build their presentation and one day to present. 

Afterward, we discuss how the model has changed over time. The limitations of each model are mentioned. I also like to point out that while Bohr’s model is no longer technically correct, it is more useful for teaching than the cloud model. 
Atomic Structure
1 day		Atomic Structure Notes + PracticeWe take formal notes on atomic structure, discussing protons, neutrons, and electrons. Students learn how to represent atoms with a shorthand notation (isotope notation). They practice counting subatomic particles based on that isotope notation and vice-versa.
Depending on the class, I will sometimes complete the practice together and give them an additional practice page. If they are really strong, I’ll have them attempt the practice page independently, and we’ll check it together at the end of class. 
Isotopes
2 days		Isotopes POGIL

Isotope Notes + Practice		The Isotopes POGIL answers the question, “are all atoms of an element alike?”. Students are exposed to several models, which lead them to realize that isotopes of an element exist and that each element may have a different number of isotopes. 
Average Atomic Mass
3-4 days		Average Atomic Mass Lab

Post-Lab Discussion

Notes + Practice		Students are given a sample of “candium” (a mixture of plain and peanut M&Ms). You can replace the candy with anything: paperclips, washers, erasers, whatever- as long as there are at least 2 types of the same thing. You can also add a 3rd or 4th isotope. Also, to avoid cheating, make the samples random. 

Students find the average mass of the different isotopes and are walked through calculating the average atomic mass based on their sample. 
Have students share their average atomic masses and discuss why they aren’t all the same. What factors contributed to this (random samples). Repeating this process more times would eventually result in a more accurate average atomic mass. 

Next, students take notes that help them solidify what they’ve discovered during the lab and class discussion. 
Intro to Ions
1 day		Intro to Ions Notes

Comparing Atoms, Ions, and Isotopes

Whiteboard Practice		There is another variation on the atom, the ion. Instead of a difference in neutrons, ions have an unbalanced number of protons and electrons. I like to go through these notes and ask students what they remember from middle school about ions. 

Once the notes are complete, I pull up a reference page that compares atoms, ions, and isotopes on the same page so that we can discuss the differences. 

To practice using these different notations, I’ll have students use whiteboards to write the symbols or names of different atoms, isotopes or ions that I write on my board. I do this randomly, but if you’d like me to discuss more in length or would like a document, let me know in the comments!
ReviewVocabulary Review

One-Pages and/or discussion		Before the assessment, I like to ask my students to list the new things they’ve learned about the atom. We are always building on previous ideas, and it’s important to take the time to recognize that. Students are usually shocked to see how much richer their understanding of atoms is after this unit. This also helps to encourage them to study. At this point in the year, some students think they have already learned enough chemistry to get by in middle school, which can lead to bad habits, like not preparing for an assessment.
Assessment

Further Reading

Atoms Notes Bundle on TeachersPayTeachers, TPT

The Chemistry Particle’s Guide to Teaching High School Chemistry, The Chemistry Particle

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