Summary

In this activity, students will learn how to apply the Aufbau principle, Pauli exclusion principle, and Hund’s rule to model electron configurations and orbital diagrams. They will use colored flat marbles to represent different directional spins of electrons as they fill orbitals based on energy level. They will then look for patterns in the electron configurations and orbital diagrams of various atoms and ions.

Grade Level

High School

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following standards:

• HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms. 
• HS-PS1-2: Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.
• Scientific and Engineering Practices
  • Developing and Using Models
  • Engaging in Argument from Evidence

Objectives

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

• Create electron configuration and orbital diagram models for various atoms and ions by following the Aufbau Principle, Pauli Exclusion Principle, and Hund’s Rule.
• Examine patterns in the electron configurations of various ions and atoms.
• Identify magnetic properties of atoms and ions based on electron configurations.

Chemistry Topics

This activity supports students’ understanding of:

• Atomic structure
• Electron configurations
• Orbital diagrams
• Electron spin
• Paramagnetism and diamagnetism

Time

Teacher Preparation: 10-20 minutes
Lesson: 60-90 minutes

Materials

• 18 flat marbles of one color and 18 flat marbles of a second color per group (flat marbles can be substituted with two different colored bingo chips or other colored markers) 
• Student handout
• Orbital Diagram Sheet

Safety

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

Teacher Notes

• Students should have been introduced to the concepts of energy levels, orbitals, valence electrons, and electron configurations prior to this activity. Depending on students’ comfort level with reading and applying new information on their own, you may also want to introduce orbital diagrams and how they relate to the Aufbau principle, the Pauli exclusion principle, and Hund’s rule, which are presented in the “Background” section of the student handout.
  • A good resource to introduce students to these topics and help them visualize how electrons are filling orbitals is an Annenberg Learner simulation that allows students to construct orbitals and fill them with electrons for several elements. The rest of the interactive module also has some helpful explanations and diagrams, though it only goes up through the 3p orbitals.
  • This activity goes through the 4p sublevel so it includes d-block elements but does not include any elements that would contain occupied f-orbitals.
  • There is space in the Background section around each of the three principles/rules for students to take notes if you wanted to go through the background information as a class before starting the activity.
• Depending on the level of your students, it could be very helpful for them to complete the activity in pairs or small groups so they can discuss their thoughts with a peer. You may want to pair students up intentionally so that students who tend to struggle with abstract concepts are working with a classmate who is stronger in that area.
• Different colored flat marbles can be purchased from Amazon.com or in many craft stores.
• The template for the Orbital Diagram Sheet can be found in the sidebar. I laminate the sheets for use across multiple classes/years and use groups of two students per sheet.
• Depending on the level of your class, it may be beneficial to have a discussion with students before/after this activity about stability (particularly as it relates to formation of ions), noble gas configurations, what electrons would be bonding electrons, and especially the exceptions to expected electron configurations in atoms such as Cr, Fe³⁺, and Cu. This will help reinforce the thought processes they should have used in the analysis questions and make sure everyone is on the same page.
  • The notion that half-filled orbitals are relatively stable (though less so than completely filled orbitals) is an important thing for students to understand when looking at the “exceptions” listed above (and other similar examples) and should be addressed in order for students to be able to get the correct configurations for those examples. This could be done as a whole class before the activity, or with each group as they reach those specific examples during the activity.
• The activity can be modified for lower levels by removing orbital diagrams, removing magnetic properties, removing the elements/ions that do not exactly “follow the rules” (Cr, Fe³⁺, and Cu), or reducing the number of atoms/ions to model.
• If students have trouble recognizing patterns in the analysis questions, it could be helpful to give them a few more examples to practice with so they have more electron configurations to compare.
• Students may ask about the subscripts on the Orbital Diagram Sheet. You could explain that they relate to the spatial orientation of the orbital (which could also be reinforced with AACT’s Orbitals Animation), or you could remove them if they will be too distracting for your students.
• Other AACT resources that could help teach this topic:
  • Lesson Plan: Electron Configuration and the Periodic Table
  • Animation: Orbitals Animation
  • Activity: Electrons & Orbitals
  • Activity: Planet P–10
  • Activity: E-config Battleship

Example of nitrogen electron configuration:

Example of chromium electron configuration: