How Structure Can Affect Properties Through Phase Changes

Structure-Property Relationships

Overview:

Middle school students will discuss how changing the structure of atoms and molecules can change the properties of a substance after watching videos and filling out worksheets. Students can brainstorm and review their own examples of phase change with the help of a phase change diagram. The idea of technology that can change the structure of materials will be introduced. An extension activity on buckyballs is available.

Content Objectives

1. Students will know that molecular arrangement determines physical characteristics.
2. Students will know that phases are physical properties.
3. Students will know why changing the structure of the molecule changes the properties of a substance.

Process Objectives

1. Students will be able to describe the molecular arrangement of various substances.
2. Students will be able to explain the structural changes occurred by a water molecule during phase changes.
3. Students will be able to label a diagram showing the phase changes of water.

Assessment Strategies

1. Completion of video review questions
2. Completion of the vocabulary worksheet
3. Construction of phase diagram and explanation

Materials

• Computers with internet access (either one for each pair of students or a projection system for the class)

• Video
Structure and Property Changes of Water (1 minute 5 seconds)
Atom Arrangements in Solids (1 minute 30 seconds)

• Worksheets
Structure-Property Relationships
Phase Change Diagram (Teachers may want to make an overhead of the answer key to the Phase Change Diagram).
Studysheet How Structure Affects Properties

•Answer Keys
Structure-Property Relationships Answer Key
Phase Change Diagram Answer Key

Procedures

Part 1: Introduction to how structure can affect properties (30 minutes)
1. Explain to the students that changing the structure of atoms and molecules can change the properties of the substance.
2. Pass out the Structure-Property Relationships Worksheet. Ask students to fill in the answers to Part 1 of the worksheet after they watch the videos and review Studysheet How Structure Affects Properties.
3. Show the video Structure and Property Changes of Water (1 minute 5 seconds).
4. Review the answers to Part 1 of the worksheet with the students.
Part 2: Completing the “Phase Change Diagram” (10 minutes)
1. Hand out the phase change diagram. Have students work on completing the diagram.
2. Review the diagram with the class by projecting it as an overhead.
3. Hold a discussion about some of the examples that students brainstormed. Focus on how the properties of the substance changed during the phase change.
4. Show the video Atom Arrangements in Solids (1 minute 30 seconds).

Part 3: Changes in structure other than phase changes (5 minutes)
1. Explain that structure changes are caused by phase changes. We can also change the structure using new technology.

Extension

Have students explore Buckyballs. This is another structural change of carbon. Students can explore how the atoms were rearranged and what different properties are exhibited. Students can also explore the difference between crystalline structures, where atoms are arranged in a set pattern, and amorphous structures, where atoms are not arranged in set patterns. Have students compare and contrast the properties of crystals like quart, salt, and diamonds, with the properties of amorphous solids like glass and silly putty. How does the structure affect the properties of each?