Download VSEPR pHeT - Northwest ISD Moodle

Name:_____________________________ Per:_____
Directions:
- Find and run the PhET Simulator: Molecular Shapes
- Follow the guide below.
https://phet.colorado.edu/en/simulation/molecule-shapes
Learning Goals: Students will be able to:
 Identify substances to which “Molecular geometry” applies.
 Name molecule and electron geometries for basic molecules.
 Explain the model being used to predict molecule geometry.
 Predict common molecular geometry from the number of electron pairs and bonded atoms around a central atom of basic
compounds.
1. Click the play button, then click on model, click on molecule geometry, electron density, show bond angles.
2. Add single, double, triple bonds, or lone pairs.
Guiding Questions:
(“groups” could mean lone pairs, single, double, or triple bonds)
1. Identify substances to which “Molecular geometry” applies: (which of the three kinds of bonding we have studied)
2. Explain –
a. What seems to be the basic model for how groups are arranged? (what happens to existing groups when a
new one is added, and what is causing that?)
b. What appears to be the major differences between “lone pairs” and the other items that can be attached to
the central atom? (especially as it relates to the molecular/electron geometry difference)
c. What is the main difference between the Molecular Geometry and the Electron Geometry? (hint: try
clicking and unclicking the “show lone pairs option after you build H2O)
3. Explore what molecules you can build. Build every combination you can IF you assume you can only do EIGHT
electrons worth on the central atom, even though the model will let you break that rule.
a. What are the combinations of attached groups, atoms, or lone pairs you can add to a central atom?
b. How does the number of groups help define the Electron geometry and the Molecular Geometry? (or
what shapes do you tend to get for different combinations. Give a few examples.)
c. What are the names of the different geometric shapes?
d. What affects the bond angles?
Only after you have completed the front page, try these examples!
Chemical
Formula
H2O
*BH3
(boron =
max 3
bonds)
HCN
NH3
CH4
SO2
PI3
CO2
N2
Lewis Dot
Structure
# lone
pairs
(on
central
atom)
# bonded
pairs (on
central
atom)
Electron Geometry
Molecular Geometry and
hybridization of the central
atom