CHE 201
MOLECULAR GEOMETRY: LEWIS STRUCTURES, VSEPR THEORY AND VALENCE BOND THEORY
SEQ CHAPTER \h \r 1LABORATORY REPORT: MOLECULAR GEOMETRY - LEWIS STRUCTURES & VSEPR THEORY
PROCEDURE:
Look to the example of ammonia (NH3) as a guide. On the following pages, for each molecular formula:
1.
Calculate the number of valence electrons to be included in the structure;
2.
Draw the co
ect Lewis dot structure;
3.
Indicate the number of electronic regions around the central atom;
4.
What is the electronic geometry around central atom;
5.
How many lone pairs of electrons (nonbonding pairs) are around central atom;
6.
What is the molecular geometry around central atom;
7.
IDEAL existing bond angles around central atom (Note: Do not report anything other than 90°, 109.5°, 120° and/or 180° and do not report bond angles that do not exist in the structure drawn); and
8.
The overall polarity within the molecule (polar or nonpolar).
You may need to assign formal charges to determine the co
ect a
angement of the electrons. The octet rule must apply for C, N, O and F. Molecules marked with an asterisk (*) do not obey the octet rule.
Molecula
Formula
1. # Valence Electrons
2. Lewis Structure
3. Number of Electron Regions
4. Electronic
Geometry
5. Number of Lone Pairs
6. Molecula
Geometry
7. IDEAL
Existing
Bond Angles
8. Overall Polarity
NH3
5+3(1)= 8e-
..
H — N — H
|
H
4
tetrahedral
1
trigonal
pyramidal
109.5ÌŠ
Pola
SBr2
_______
CHCl3
_______
AsO43-
(violates
octet rule)
_______
HCN
_______
*KrS2
(violates
octet rule)
_______
CH2O
(C is the central)
_______
CSO
(C is the central)
_______
*KrCl2
(violates
octet rule)
_______
*ICl4+
(violates
octet rule)
_______
*SBr4
(violates
octet rule)
_______
*XeCl6
(violates
octet rule)
_______
SO2
(violates
octet rule)
_______
*KrI4
(violates
octet rule)
_______
*SeCl5+
(violates
octet rule)
_______