Lab 6 MOLECULAR GEOMETRY Objectives Correlate Lewis dot structures with electron domain geometries View the effect of lone pairs of electrons on molecular.
Download
Report
Transcript Lab 6 MOLECULAR GEOMETRY Objectives Correlate Lewis dot structures with electron domain geometries View the effect of lone pairs of electrons on molecular.
Lab 6
MOLECULAR GEOMETRY
Objectives
Correlate Lewis dot structures with electron
domain geometries
View the effect of lone pairs of electrons on
molecular shape
Materials
5 molecular models representing the 5 basic
electron domain geometries
13 balloon models representing the 13 different
molecular geometries
How to determine the 3D
structure of a molecule
Step 1: Draw the Lewis structure
Step 2: Determine electron-domain geometry
around the central atom.
Step 3: Determine the molecular geometry
Step 2:
Determine electron
domain geometry
VSEPR theory – a model used to predict the 3D
structure of individual molecules. This theory is
based on the idea that electrons repel each
other.
Electron domain geometry describes the
geometric arrangement of electrons around an
atom (bonds and/or lone pair(s) of electrons).
Step 2:
Determine electron
domain geometry
There are 5 basic electron domain geometries
1.
2.
3.
4.
5.
Linear
Trigonal planar
Tetrahedral
Trigonal bipyramidal
Octahedral
Step 3:
Determine the
molecular geometry
Linear
Trigonal Planar (Bent)
Tetrahedral (trigonal pyramid; bent)
Trigonal bipyramidal (Seesaw; T shaped)
Octahedral (Square pyramid; square planar)
(Show some examples and diagrams)
Lab 6: Procedure/Data
Collection
Station 1 – Lewis Structures and Molecular
Models
- 1 set of eight substances (Table 2 pg
64) are assigned (workshop handout).
- In the lab, match the Lewis structure
to one of the 5 molecular models on the
lab bench.
-(Table 3 pg 65) Identify the correct model
number (and molecular formula), name
the electron-domain geometry, draw the
3D structure, and label all ideal bond
angles.
Lab 6: Procedure/Data
Collection
Station 2 – VSEPR and Balloon Models: effect of
lone pairs on molecular shape.
- Again, you are to match the Lewis
structure (from workshop) to one of the
balloon models representing
VSEPR structures.
-Balloons represent the space occupied
by either bonding pairs or lone pairs.
Station 4 – cont.
(Table 4 pg 67 & 68)
Identify the VSEPR model number
Name the molecular geometry (shape) (e.g.
Bent, Seesaw, T shaped etc.)
Draw the 3D structure
Label all bond angles in your structure, indicating
distortions using “<“ or “>” signs.
At the end of the lab…
Turn in today’s lab write-up and all of the
workshop handouts.
Lab 9 write-up, naming compounds H.W. and lab
6 (handout from last week) are due in the
beginning of the lab.