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McREL Standards Activity

Modeling Chemical Bonding

Purpose:As a result of this activity, students will be able to understand that atoms form bonds according the properties of atoms.
Related Standard & Benchmarks:
 Standard 8.Understands the structure and properties of matter
   Level IV [Grade 9-12]
   Benchmark 4. Knows that atoms may be bonded together into molecules or crystalline solids, and compounds are formed from chemical bonds between two or more different kinds of atoms
Student Product:Models of chemical compounds
Material & Resources:Commercial set of chemical models or styrofoam balls and toothpicks, textbook or reference book that shows the configurations of molecules.
Teacher's Note:This activity assumes that students have been introduced to the basic concepts of bonding and valence electrons. If styrofoam balls are used to represent atoms, they should be distinguished by being of different sizes and/or being colored or marked.
Students will be provided with plastic models or styrofoam balls that represent atoms and toothpicks to represent bonds. Each student or group will need at the minimum: 1 Carbon atom 1 Nitrogen atom 2 Oxygen atoms 3 Chlorine atoms 4 Hydrogen atoms Each student or group will then construct models of selected compounds. Each model should have the correct number of bonds for each atom (i.e., 1 for Hydrogen and Chlorine, 2 for Oxygen, 3 for Nitrogen, and four Carbon). Models should also accurately reflect the configuration of the molecule in space. The models to be constructed are: 1 NH3 (Ammonia) 2 CH4 (Methane) 3 H2O (Water) 4 Cl2 (Chlorine Molecule) 5 O2 (Oxygen Molecule) 6 CO2 (Carbon Dioxide) 7 CHCl3 (Chloroform) After all models have been constructed (or after each model if there are not enough materials) students are to check a reference book to see if their models are correct. Students should investigate and report in writing or in a class discussion why certain molecules do not have a symmetrical configuration (e.g., NH3, H2O).