Constructing Molecular Models Name: ______

Molecules have three-dimensional shapes that depend on the ways in which the atoms in the molecules are bonded together. Many molecular model kits use colored balls and connectors to represent atoms and bonds. A structure formed by joining these balls and connectors will approximate the actual shape of a molecule.

The “atoms” in a molecular model kit are color-coded:

H = white O = red CI = green I = purple C = black N = blue Br = orange

In a molecular model, if two balls are joined together by a connector (stick/nonflexible plastic), the connector represents a covalent bond composed of two electrons. If two balls are joined together by two connectors (springs/flexible plastic), a double covalent bond composed of two electron pairs (four electrons) is indicated. Three connectors (springs/flexible) joining two balls represent a triple covalent bond composed of three electron pairs (six electrons).

Nonpolar Bonds have an electronegativity difference (ΔEN) from 0.0 – 0.4; Polar bonds have an electronegativity difference from 0.5 – 1.7. The electronegativity values for the elements are:

H: 2.1 O: 3.5 CI: 3.0 I: 2.5 C: 2.5 N: 3.0 Br: 2.8

Instructions

Construct molecular models of each of the compounds listed in the data table using as many connectors as possible to join atoms in each model. Sketch a 3D diagram of what the molecular model looks like and name the shape of the molecule (linear, trigonal planar, bent, trigonal pyramidal, tetrahedral). Determine each bond’s electronegativity difference, draw the Lewis structure (using 0 to show polarity), determine the bond (single, double, or triple), and molecule type (polar or nonpolar). Room temperature states of matter are provided for you to research their relationship to their polarity and VSEPR shape prior to taking Physics II: E&M and/or Organic Chemistry.

Questions

1. What type of bond is involved in the models you constructed in Parts A, B, C, and D? ______

2. What type of bond is common to the three models you constructed in part E? ______

3. What type of bond is common to the three models you constructed in part F? ______

4. Which of the models that you constructed represent diatomic molecules?

5. On the basis of your results, what bond combinations must be present in order for a triatomic molecule to be linear?

6. Why do you think you were instructed to use as many connectors as possible to join atoms in each model?

7. Diatomic Molecule Research #1: If I2 is a linear nonpolar molecule, why is it a solid at room temperature?

8. Diatomic Molecule Research #2: If CO is a linear polar molecule, why is it a gas at room temperature? Constructing Molecular Models Polar/ Bond: State of 3D Sketch of the Name the Lewis Structure Part Molecule ΔEN Nonpolar – / =/ ≡ Matter Molecule Shape (Use 0 for polarity) (N/P) (S,D,T) (S,L,G)

A H2 G

Cl2 G

Br2 L

I2 S

HCl G

HBr G

B CH4 G

CCl4 L

C NH3 G

D H2O L

Cl2O G

E O2 G

CO2 G

H2CO G

F N2 G

CO G

HCN L

C2H2 G