Molecular Structures & Designed Materials: A Phenomenon-Based Inquiry

Estimated Time: 45-60 minutes Materials Needed: Internet-connected device, student handout/notebook.

Part 1: Engage (Anchoring Phenomenon)

The Challenge: You have been hired as a Junior Materials Scientist at NanoStruct Innovations. Your first assignment is to evaluate three different materials for specific client applications: high-efficiency electrical wires, impact-resistant flexible gear, and targeted pharmaceuticals. Your supervisor has noticed that while many engineers understand the macroscopic properties of these materials (e.g., “it stretches”), they often cannot explain why the materials behave that way at the molecular level. Your job is to analyze the relationship between the molecular-level structure and the function of each designed material.

Initial Reflection:

1. Why do you think metals are typically used for electrical wires rather than plastics?
2. What makes a rubber band stretchy, but a piece of glass brittle?
3. How does a medicine “know” exactly which cells in the body to affect?

Part 2: Explore (Simulation Investigation)

Open the Molecular Structures & Designed Materials Simulation. You will use the simulation’s three modules to collect data on different materials.

Module 1: Electrical Conductivity (Metals)

1. Select the Electrical Conductivity (Metals) tab.
2. Observe the “Sea of Electrons” model. Note the arrangement of the metal cations (positive ions) and the behavior of the delocalized electrons.
3. Toggle the Apply Voltage switch to the ON position.
4. Observation: Describe what happens to the electrons when voltage is applied. How does this movement explain electrical conductivity?

Module 2: Flexibility (Polymers)

1. Switch to the Flexibility (Polymers) tab.
2. Observe the arrangement of the polymer chains in their initial “coiled” state.
3. Slowly increase the Mechanical Stress slider from 0 to 100.
4. Observation: Describe how the structure of the long-chained molecules changes as mechanical stress is applied. What happens when the stress is released?

Module 3: Receptor Docking (Pharmaceuticals)

1. Switch to the Receptor Docking (Pharmaceuticals) tab.
2. Observe the “Cellular Receptor” located on the cell membrane at the bottom of the screen. Pay close attention to its specific geometric shape.
3. Test Drug A, Drug B, and Drug C by clicking their respective buttons.

Data Collection Table: | Drug Tested | Shape of Drug Molecule | Observation / Reaction at Receptor | | :— | :— | :— | | Drug A | | | | Drug B | | | | Drug C | | |

Part 3: Explain (Sensemaking)

Use your observations from the simulation to answer the following questions:

1. Metals: How does the specific molecular-level structure of metals (the “sea of electrons”) make them uniquely suitable for their intended function (conducting electricity)? Reference the attractive and repulsive forces at play.
2. Polymers: How does the structure of long-chained polymer molecules allow the material to be flexible and durable? Why does this structure allow the material to stretch without breaking immediately?
3. Pharmaceuticals: Based on your tests, explain the “Lock & Key” model of pharmaceutical design. Why is the exact molecular shape (structure) critical for the drug to function and trigger a cellular response?

Part 4: Elaborate & Evaluate (Argumentation & Modeling)

Final Report to Clients: Draft a short technical report (2-3 paragraphs) or create a labeled diagram that communicates scientific information to your clients. Your communication must:

• Describe the intended function of one of the three materials investigated (metal wire, flexible polymer, or targeted drug).
• Explicitly describe the molecular-level structure of the chosen material (e.g., freely moving electrons, long-chained molecules, or specific geometric shapes).
• Provide evidence for why the molecular-level structure is critical to the functioning of the designed material. How do the attractive/repulsive forces and the arrangement of atoms at the atomic scale determine the macroscopic properties and function of the material?

Extension Option: Research a real-world disease (like COVID-19 or HIV) and explain how researchers used the specific molecular structure of the virus’s surface proteins to design targeted treatments or vaccines.

Teacher Notes & Alignment

NGSS Performance Expectation:

• HS-PS2-6: Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.

Alignment & Evidence of Learning:

• SEP (Obtaining, Evaluating, and Communicating Information): In Part 4, students communicate scientific and technical information about the relationship between molecular structure and material function in written or graphical format.
• DCI (PS2.B: Types of Interactions): In Part 3 and 4, students explain how attraction and repulsion between electric charges at the atomic scale (e.g., delocalized electrons in metals, intermolecular forces in polymers, geometric fit in receptors) determine the macroscopic properties of matter.
• CCC (Structure and Function): Throughout the task, students conduct a detailed examination of the molecular structures of different components to reveal how they enable the specific functions of designed materials.

Evidence Statements Addressed:

• 1.a. Students use at least two different formats (e.g., written report, graphical diagram) to fully describe the structure, properties, and design of the chosen material.
• 2.a. Students identify and communicate evidence for why the molecular-level structure is important to the functioning of designed materials.
• 2.b. Students explicitly identify the molecular structure of the chosen designed material(s) (e.g., freely moving electrons, coiled chains, geometric shapes).
• 2.c. Students describe the intended function of the chosen material(s).
• 2.d. Students describe the relationship between the material’s function and its macroscopic properties, including the ability of electrons to move freely in metals, and the molecular-level structure.