Molecular Modelling and Bonding Lab


Author:
Kevin Patrak
Secondary Science Teacher
35 Mathews Ave #31, Waterville
(207) 873 0822
Messalonskee High School

Grade Levels: 10-12 chemistry students

Objective:
The student will be able to predict bond type, structural formula, hybridization, polarity, and three-dimensional structures using ball and stick models.

 

Maine Learning Results objectives:
Science and Technology
E.  Structure of Matter ? Students will understand the structure of matter and the changes it can undergo.  Students will be able to describe how atoms are joined by chemical bonding.
L.  Communication ? Students will communicate effectively in the application of science and technology.  Students will be able to make and use appropriate symbols, pictures, diagrams, scale drawings, and models to represent and simplify real-life situations and to solve problems.
L.  Communication ? Students will communicate effectively in the application of science and technology.  Students will be able to critique models, stating how they do and do not effectively represent the real phenomenon.

Materials & Resources:
Lab-Aids - Molecular Model Kit
Student worksheet ? Bonding Lab
Internet site:  http://www.eosc.osshe.edu/chemweb/main.html

Main Ideas:

 1.  Bond Type ? Ionic or Covalent

 2.  Lewis Dot Diagrams ? use to initialize thought about the molecule

3. Structural formula ? Similar to Lewis dot diagram, but use lines to represent a bond between a covalent molecule and do not show non-bonding electrons.

4. Hybridization should be shown on the structural formula.

5. Three-dimensional representation should be drawn.  A tetrahedral representation should be a 4-sided pyramid (see example on worksheet).

6.  Polarity ? any dipole moment should be shown on the drawing.

7.  Internet address ? Go to site and click on Molecular Modeling.  Go to the bottom of the page and click on the ">>" to proceed to a listing of the contents of the site.  Click on Relationship of Molecular Shape to Electron Pair Geometry.  Students should then view each example and Diagram for the sample molecules.  This action should be done only if the students cannot determine the required information.  It may also be used as a reinforcement for prior information.

Assignment:
Have students produce a write-up in a lab notebook or whatever format you choose.  The bond type, Lewis Dot Diagram, structural formula, hybridization, and 3-D representation should be given for each molecule.

Summary:
The teacher will demonstrate the concept of molecular modeling and knowledge of structure based on models.  Students will be able to predict structures, polarity, hybridization, and arrangement of atoms within a molecule.

Molecular Bonding Lab

Use the model kits as needed to determine the structure for the following compounds.

 CH3Cl   H2O   CH4    Cl2

 H2S   CO2   NH3    NH4+

 HCl   HNO3   H2SO4   HCCl3

 C2H6   SO2   CH2O

For the lab write-up:
1) Indicate bond type (covalent or ionic)
2) Give Lewis Dot Diagram
3) Show Structural formula (covalent only)
4) Indicate hybridization (if applicable)
5) Give 3-D representation for compounds and give proper names for the structure.

1) Show polarity by d+ or d- and show any dipole moment where applicable.

Key for Model Kits:
Black --Carbon
Red -- Nitrogen
Green -- Chlorine
Blue -- Oxygen
Yellow -- Sulfur
White -- Hydrogen
16 Plastic covalent bonds
1 Plastic electron bond


This curiculum project was funded by the Colby Partnership for Science Education, the Howard Hughes Medical Institute, and the Bell Atlantic Foundation.