Summary

The AACT high school classroom resource library has everything you need to put together a unit plan for your classroom: lessons, activities, labs, projects, videos, simulations, and animations. We constructed a unit plan using AACT resources that is designed to teach Atomic Structure to your students.

Grade Level

High School

NGSS Alignment

The teaching resources used in this unit plan 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-PS1-7: Use mathematical representation to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.
• HS-PS1-8: Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.
• HS-PS4-1: Use mathematical representations to describe a simple model for waves that includes how the amplitude of a wave is related to the energy in a wave.
• HS-PS4-3: Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.
• HS-PS4-4: Evaluate the validity and reliability of claims in published materials of the effects that different frequencies of electromagnetic radiation have when absorbed by matter.
• HS-ESS1-2: Construct an explanation of the Big Bang theory based on astronomical evidence of light spectra, motion of distant galaxies, and composition of matter in the universe.
• Scientific and Engineering Practices:
• Using Mathematics and Computational Thinking
• Developing and Using Models
• Analyzing and Interpreting Data
• Engaging in Argument from Evidence
• Obtaining, Evaluating, and Communicating Information

Objectives

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

• Identify that all matter is made of one or more of the atoms of the 118 elements on the periodic table. 
• Begin to understand how small atoms are and how many of them are in small objects.
• Explain the specific contributions of Democritus, Aristotle, John Dalton, J.J. Thomson, Ernest Rutherford, Niels Bohr, Edwin Schrodinger, Albert Einstein, and Werner Heisenberg.
• Understand past and current theories regarding the structure of the atom.
• Use the number of protons, neutrons, and electrons in an element to predict an atom’s identity.
• Calculate atomic mass.
• Calculate atomic number.
• Understand the meaning of ion.
• Convert mass data for an element or a compound into values of moles, atoms or molecules.
• Explain how the atomic mass shown on the periodic table for an element was determined.
• Define an isotope.
• Accurately calculate the average atomic mass of an element given the atomic mass of each isotope and its abundancy.
• Explain the meaning of a weighted average and calculate it.
• Identify which subatomic particle(s) affect the atomic mass of an atom.
• Define an ion.
• Predict the charge an ion will have.
• Determine the atomic mass from a mixture of isotopes.
• Discuss the mass number in relation to an atom’s protons and neutrons.
• Understand the law of conservation of matter.
• Visualize how orbitals are superimposed upon one another within an atom.
• Explain the meaning of conservation of energy.
• Describe that when energy is added to an atom its electron(s) are able to temporarily move to an excited state. Energy is emitted when the atom returns to its ground state.
• Understand that energy is quantized.
• Use flame tests to identify a metal or metallic salt by the color that it produces when it is put into a flame.
• Calculate the frequency of light given its wavelength.
• Calculate the wavelength of light given its frequency.
• Identify an unknown metal by the color it emits when passed through a flame.

Chemistry Topics

This unit supports students’ understanding of

• Atomic Structure
• Atomic Theory
• Model of the Atom
• Subatomic Particles
• Atomic Mass
• Atomic Number
• Isotopes
• Orbitals
• Electrons
• Atomic Spectra
• Electromagnetic Spectrum
• Quantitative Chemistry
• Measurement
• History of Chemistry
• Chemical Reactions
• Balancing Chemical Equations
• Law of Conservation of Matter
• Law of Conservation of Energy
• Activity series

Time

Teacher Preparation: See individual resources.

Lesson: 7-10 class periods, depending on class level.

Materials

• Refer to the materials list given with each individual activity.

Safety

• Refer to the safety instructions given with each individual activity.

Teacher Notes

• The activities shown below are listed in the order that they should be completed.
• The teacher notes, student handouts, and additional materials can be accessed on the page for each individual activity.
• Please note that most of these resources are AACT member benefits.

Atomic Theory:

• The Atoms Animation uses analogies to help students visualize the size of an atom. It’s a great introductory video to start off the unit. The accompanying lesson plan contains general and extension questions to check for understanding.
• Founders of Chemistry Series: Introduce the development of atomic theory by using one or more of our Founders of Chemistry videos. The Ancient Chemistry Video traces the history of chemistry from the discovery of fire, through the various metal ages, and finally to the great philosophers. Students can learn about Rutherford's initial research on alpha particles in the Ernest Rutherford Video and hear about how he hypothesized that they were helium nuclei. The Niels Bohr Video tells the story of Niels Bohr, a great scientist who redefined how we think about atoms and the electron. Each of these includes an activity sheet that include questions for students to answer as they watch the videos.
• The Scientists Behind the Atom Project: After viewing the videos, use this project to have your students create a digital or paper book about the scientists who contributed to our understanding of the atom. This project will help students explain the specific contributions of several scientists and understand past and current theories regarding the structure of the atom.
• Indirectly Measuring the Atom: To help students better connect with Rutherford’s Gold Foil Experiment, consider having students complete this activity. Students will drop a marble 150 times on a sheet of carbon paper and use the resulting marks where the marble fell to make estimates about the measurement of the diameter of a small circle on the paper. Each marble drop is similar to an alpha particle fired at the gold foil.
• Modeling Atomic Theories with Food. One of the benefits of this activity is that is has students model what an atom looks like based on their prior knowledge. Students then amend the model over time as they are introduced to each new model of the atom, ending with a model that shows the closest representation to what we know the atom to be like today. The focus on the science and engineering practice of Developing and Using Models makes this a welcome NGSS addition.
• Building an Atom Simulation: Additionally, use this simulation to have your students manipulate the number of protons, neutrons, and electrons in an element and determine how these effect the mass number, atomic number, and other properties of an atom. This lesson, which is guided by a PhET simulation, allows students to see how they can use the number of protons, neutrons, and electrons in an element to predict its identity.

Ions, Isotopes, and Average Atomic Mass:

• Introduce the concept of isotopes with the What are Isotopes? Video Questions. Students watch a video that is part of the American Chemical Society video series Chemistry Basics and then answer questions about isotopes. This activity will help them learn about the discovery of isotopes, the difference between chemical and nuclear reactions, different kinds of radioactive decay, and some uses of radioactive isotopes.
  
• Isotopes & Calculating Average Atomic Mass: Students can learn how the average atomic mass is determined through a tutorial based on the isotope abundance for Carbon with this simulation. They then select the number of isotopes, the mass of each isotope, as well as the abundance of each to successfully build a mystery element and calculate its average atomic mass.
  
• Beanium Isotopes: If you prefer a hands-on activity, this lab will lead your students through the steps that they will take to calculate the average atomic mass of an imaginary element called Beanium.
• Candy Isotopes & Atomic Mass: This is an alternate activity you can use to introduce the concept of average atomic mass. This simple and inexpensive lesson uses M&M candies to model ratios that approximate real world atomic mass values on the periodic table. The resource can be used with middle or high school students and includes alignment with NGSS performance expectations.
• The Electrons and Ions Explained with Balloons activity is a great analogy for how gaining or losing electrons affects the properties of an atom. Clothespins that represent electrons are added or removed from a helium balloon, causing the height of the balloon in the air to change. Consider using this for visual learners.

Conservation of Mass:

• Antoine Lavoisier: Introduce the concepts of conservation of mass and the law of definite proportion with this Founders of Chemistry video, which tells the story of how, who many consider to be the father of modern chemistry, discovered oxygen and hydrogen and first proposed the Law of Conservation of Mass. It also includes an activity sheet that includes questions for students to answer as they watch the videos.
• Balancing Legos: Following the video, have your students use this hands on activity to model the reactants and products in a chemical reaction. They then use these “atoms” and “molecules” to balance the chemical reaction to demonstrate the law of conservation of matter.
• Chemistry in a Bag: Use this lesson as an activity or a demonstration to have your students make observations about the Law of Conservation of Mass.

Electrons, Electron Configurations, and Electromagnetic Radiation:

• Emissions of Light: This makes a great phenomena-based lab. Students can explore different emissions of light. You can ask probing questions about where the energy came from to give off light and then return to the questions once you have taught students about electron transitions and light.

• Orbitals Animation: With the use of the Bohr model to introduce atomic structure, students visualize electrons “orbiting” around the nucleus. Help them expand their knowledge with this animation, which allows students to visualize how orbitals are superimposed upon one another within an atom in three dimensions. The orbitals depicted in this animation are 1s, 2s, 2p, 3s, 3p, 4s, and 3d.

• Follow up with the lesson, Electrons and Orbitals to help students differentiate between energy levels, sublevels, orbitals, and electrons. Students often confuse these terms related to electrons and this activity helps them develop a stronger understanding of how to distinguish between them.

• Flame Test (Rainbow Demo): Finish up your study of electrons with this safer version of the traditional demonstration that is commonly used in high school chemistry classrooms. It can be used to show students the variety of colors that are produced when different metallic salts are heated in a flame. You can view a video of this demonstration on The Flame Test page of the ACS website. Read more about this in the ACS Safety Alert about the Rainbow Demonstration.

• Flame Test: Going Further: In additions to the demonstration, have your students investigate the colors produced when several mixtures of metallic ions are placed in a flame. Note that this procedure also uses wooden splints and aqueous solutions in place of the traditional flammable solvent.