Name: _______________ _______________
Class: CHEM2215 Section: _____
Molecular Geometry Lab
Pre-Lab Assignment
1. ___________ theory predicts that there are regions of electrons in an atom based on placing
shared pairs of valence electrons between bonding nuclei and unshared valence electrons
located on single nuclei.
2. VSEPR theory stands for:
______________ ______________ ______________ ______________ ______________
3. Draw the 2-dimensional and 3-dimensional Lewis structures for ammonia.
4. Complete the following table:
5. Give an example of a molecule with octahedral geometry.
Molecular Structure Lab
Name: _______________ _______________
Class: CHEM2215 Section: _____
Molecular Structure Lab
Theory
Valence shell electron pair repulsion (VSEPR) is a theory used to predict the shape of molecules
based upon the extent of electron-pair electrostatic repulsion.
The premise of VSEPR is that the electron pairs surrounding an atom mutually repel each other,
and will therefore adopt an arrangement that minimizes this repulsion, and maximizes their
separation. The electron pairs may be either bonding pairs or lone pairs.
The resulting geometric arrangement allows us to predict the shapes and bond angles of
molecules.
Objective
To investigate molecular structure.
Apparatus
Molymod model kits.
Method
Construct and draw molecular models for each ion/molecule below. Indicate the number of
electronic groups, the parent shape (electronic geometry) and the derivative shape (molecular
geometry).
Molecular Structure Lab
Name: _______________ _______________
Molecule
or Ion
2-D Structure
Class: CHEM2215 Section: _____
Shape
#of Electron Groups______
1. CCl4
Parent
Shape______________
Derivative Shape (if any)
______________________
#of Electron Groups______
2. AsF3
Parent
Shape______________
Derivative Shape (if any)
______________________
#of Electron Groups______
3. SbF5
Parent
Shape______________
Derivative Shape (if any)
______________________
#of Electron Groups______
3-
Parent
Shape______________
4. PO4
Derivative Shape (if any)
______________________
2-
#of Electron Groups______
5. SO4
Parent
Shape______________
Derivative Shape (if any)
______________________
Molecular Structure Lab
3-D Structure
Name: _______________ _______________
Molecule
or Ion
2-D Structure
Class: CHEM2215 Section: _____
Shape
#of Electron Groups______
6. C2H2
Parent
Shape______________
Derivative Shape (if any)
______________________
#of Electron Groups______
7. C2H4
Parent
Shape______________
Derivative Shape (if any)
______________________
+
#of Electron Groups______
8. NH4
Parent
Shape______________
Derivative Shape (if any)
______________________
#of Electron Groups______
9.
C2H5OH
Parent
Shape______________
Derivative Shape (if any)
______________________
#of Electron Groups______
10. BrF3
Parent
Shape______________
Derivative Shape (if any)
______________________
Molecular Structure Lab
3-D Structure
Name: _______________ _______________
Class: CHEM2215 Section: _____
Questions
1. Describe the geometry of the acetic acid molecule.
2. Describe the geometry of the methylamine molecule (CH3NH2)
3. Describe the geometry of the molecule ethylenediaminetetraacetic acid (EDTA).
4. What are some uses of EDTA?
Molecular Structure Lab
Name: _______________ _______________
Molecular Structure Lab
Class: CHEM2215 Section: _____