Question

Experiment 1:

Molecular Models of Neutral Molecules

In this experiment, you will predict the three-dimensional geometry of a series of neutral molecules using the VSEPR theory.

Procedures

Part 1: Use your Periodic Table of Elements to determine the elemental symbol, group number and valence electrons for the elements listed in Table 1. 

Table 1: Lewis Dot Structures

 

Element	Symbol	Group Number	Valence Electrons	Lewis Dot Structure
Hydrogen	H
Carbon	C
Chlorine	Cl
Aluminum
Oxygen	O
Fluorine	F
Neon	Ne
Nitrogen	N

Part 2: Construct the three-dimensional geometry for the molecules listed in Table 2. 

Table 2: Molecular Models

 

Molecule (central atom is underlined)		Shape Name Bond Angle		Bond Angles (more than one may be possible)
CO2		Linear
AlCl3		Trigonal Planar
H2O		Bent
NH3		Trigonal pyramidal
CCl4		Tetrahedral
PCl5		Trigonal bipyramidal
SF6		Octahedral

Post-Lab Questions:

1. What is the molecular geometry (shape) of the methane molecule (CH4)? Explain completely why all the bond angles in methane are equal.

2. What is the molecular geometry (shape) of the chloromethane molecule (CH3Cl)? Explain completely why NOT all of the bond angles in chloromethane are equal.

3. Chloromethane can be thought of as resulting from methane via the replacement of one Hydrogen atom with a Chlorine atom. Subsequent replacements of H with Cl yield dichloromethane (CH2Cl2), trichlormethane (CHCl3) and tetrachlormethane (CCl4). Which of these three previous molecules will have all bond angles equal to each other? Explain completely.

4. Sketch the molecular shape of the compounds in the table below. Be sure to identify the bond angles. H₂ Cl₂ SO₂ NH₃ MoF₆