grc mini grant prototype storyboard #1 lewis structure and molecular geometry

GRC Mini Grant Prototype Storyboard #1

Lewis Structure and Molecular Geometry

Tracking Sheet 1.1_v1.ppt by rjh 7.2.081.1_v1.ppt by blg 7.11.08

Lewis Structure and Molecular Geometry Outline1.1 Structure and Geometry of Methane - build a 2D Lewis structure, consider 3D representations, select the correct one, observe differences. recording (slides 4-8)1.2 Structure and Geometry of Ammonia - build a 2D Lewis structure, consider 3D representations, select the correct one, observe differences. recording (slides 9-13)1.3 Structure and Geometry of Water - build a 2D Lewis structure, consider 3D representations, select the correct one, observe differences. recording (slides 14-18)1.4 The Connection to Biology - roll over activity to consider the unique properties of water resulting from its geometry/polarity. (slide 19)

Learning Goals-To understand how to go from the Lewis structure to the shape of a molecule, both based on electron pair geometry and molecular geometry.- To understand the differences between representing a molecule in two dimensional space and three dimensional space.

Barbara Gonzalez:Suggestions for learning goals expressed in terms that are amenable to assessable outcomes.After completing this module, the learner will be able to:-Determine the electron pair or steric number geometry of a molecule from a Lewis structure representation.-Determine the molecular or coordination number geometry of a molecule from a Lewis structure representation.-Compare and contrast two- and three-dimensional representations of molecules.

C H

atoms

bonds

electrons

pairs

l

.

..

(stage)

Here’s the formula for methane (CH4). Build a Lewis structure below for the methane molecule. Begin by dragging the central atom from the supply on the left to the stage in the middle.

1.1.1

Barbara Gonzalez:“Another convention that chemists use to represent shared electrons is to use a line to represent a bond. Edit your Lewis structure to conform to this convention.MetadataWhere will students be asked to explain how they built their structure?

A

B

Now that you’ve built a methane molecule in two dimensional space, let’s represent methane in three dimensional space. Below are two possible 3-D representations of a central atom bonded to four other atoms. Click start on each representation to explore the arrangement of the bonds.

square planar

tetrahedral

1.1.2

start >

start >

Barbara Gonzalez:Now that you have built a methane molecule in two-dimensional space using a Lewis structure, let’s represent methane in three-dimensional space. Below are two possible three-dimensional representations of the central atom bonded to four other atoms. Click START on each representation to explore the arrangements of the bonds in each of the representations.

Do we need a message to students who only explore one of the geometries to take a look at both of them?

A

B

stage

Now that you have explored the two possible arrangements, select which arrangement is the correct 3-D representation for methane by dragging it to the stage.

square planar

tetrahedral

1.1.3

Please explain, why did you select this representation?

Barbara Gonzalez:Please explain why you selected this representation?

A

B

stage

Now that you have explored the two possible arrangements, select which arrangement is the correct 3-D representation for methane by dragging it to the stage.

square planar

tetrahedral

1.1.4


Bonds are more stable when they are as far apart in space as possible. Have you really considered three dimensional space? Try again.

A

Click start on example A to see a 3-D representation of methane, considering only the electron pairs that surround the central atom. Click start on example B to see a representation of methane, considering only the atoms.

Electron pair geometry atom geometry

B

Notice that they are the same.

1.1.5

start > start >Barbara Gonzalez:Click START on Box A to see a three-dimensional representation of methane that depicts only the electron pairs that surround the central atom. Click START on Box B to see a three-dimensional representation of methane that depicts only the bonding electron pairs that surround the central atom.

N H

atoms

bonds

electrons

pairs

l

.

..

stage

Here’s the formula for ammonia (NH3). Create a Lewis structure below for the ammonia molecule. Begin by dragging the central atom from the supply on the left to the stage in the middle.

1.2.1

Barbara Gonzalez:“Another convention that chemists use to represent shared electrons is to use a line to represent a bond. Edit your Lewis structure to conform to this convention.MetadataWhere will students be asked to explain how they built their structure?

A

B

Trigonal planar

T shaped

C

Square planar

Trigonal pyramidal

Tetrahedral

D

E

Now that you’ve built an ammonia molecule in two dimensional space, let’s represent ammonia in three dimensional space. Below are five possible 3-D representations of a central atom bonded to three other atoms. Click start on each representation to explore the arrangement of the bonds.

stage

1.2.2

start > start >

start >start >

start >

Barbara Gonzalez:Now that you have drawn a representation of an ammonia molecule in two-dimensional space, how is the ammonia molecule represented in three-dimensional space? Below are five possible three-dimensional representations of a central atom bonded to three other atoms. Click START on each representation to explore the arrangements of the bonds.

A

B

Trigonal planar

T shaped

C

Square planar

Trigonal pyramidal

Tetrahedral

D

E

stage

1.2.3


Now that you have explored the possible arrangements, select which arrangement is the correct 3-D molecular geometry for ammonia by dragging it to the stage.

Barbara Gonzalez:Now that you have explored the possible arrangements, select which arrangement is the correct three-dimensional geometry for ammonia by dragging it into the stage.

Barbara Gonzalez:Please explain, why you selected this representation.

A

B

Trigonal planar

T shaped

C

Square planar

Trigonal pyramidal

Tetrahedral

D

Estage

1.2.4


Bonds are more stable when they are as far apart in space as possible, have you really considered three dimensional space? Try again.

Now that you have explored the possible arrangements, select which arrangement is the correct 3-D molecular geometry for ammonia by dragging it to the stage.

Barbara Gonzalez:Now that you have explored the possible arrangements, select which arrangement is the correct three-dimensional geometry for ammonia by dragging it into the stage.

Barbara Gonzalez;Bonds are more stable when they are as far apart in space as possible. Have you really considered three dimensional space? Try again.

Barbara Gonzalez:Please explain, why you selected this representation.

A

Click start on example A to see a 3-D representation of ammonia, considering only the electron pairs that surround the central atom. Click start on example B to see a representation of ammonia, considering only the atoms.


B

Notice that the two geometries are different. The electron pair geometry considers all of theregions of electron density and the molecular geometry considers only the atoms bonded to the central atom.

1.2.5

start > start >

Barbara Gonzalez:Click START on Box A to see a three-dimensional representation of the ammonia molecule that depicts only the electron pairs that surround the central atom. Click START on Box B to see a three-dimensional representation of the ammonia molecule that depicts only the bonding electron pairs that surround the central atom.

O H

atoms

bonds

electrons

pairs

l

.

..

stage

Here’s the formula for water (H2O). Build a Lewis structure below for the water molecule. Begin by dragging the central atom from the supply on the left to the stage in the middle.

1.3.1

Barbara Gonzalez:“Another convention that chemists use to represent shared electrons is to use a line to represent a bond. Edit your Lewis structure to conform to this convention.

A

B

bent

linear square planar

tetrahedral

C

D

Now that you’ve built a water molecule in two dimensional space, let’s represent water in three dimensional space. Below are four possible 3-D representations of a central atom bonded to two other atoms. Click on each representation to explore the arrangement of the bonds.

stage

1.3.2

Barbara Gonzalez:Now that you have drawn a representation of a water molecule in two-dimensional space, how is the water molecule represented in three-dimensional space? Below are five possible three-dimensional representations of a central atom bonded to two other atoms. Click START on each representation to explore the arrangements of the bonds.

A

B

bent


tetrahedral

C

D

stage

Now that you have explored the possible arrangements, select which arrangement is the correct 3-D molecular geometry for water by dragging it to the stage.


1.3.3


Barbara Gonzalez:Now that you have explored the possible arrangements, select the correct three-dimensional representation for the molecular geometry of water by dragging it to the stage.

A

B

bent


tetrahedral

C

D stage

1.3.4


Now that you have explored the possible arrangements, select which arrangement is the correct 3-D molecular geometry for water by dragging it to the stage.

Bonds are more stable when they are as far apart in space as possible. Have you really considered three dimensional space? Try again.


A

Click start on example A to see a 3-D representation of water, considering only the electron pairs that surround the central atom. Click start on example B to see a representation of water, considering only the atoms.


B

1.3.5

Are these two geometries the same? Why or why

not?

start > start >

Barbara Gonzalez:Click START on Box A to see a three-dimensional representation of a water molecule that depicts only the electron pairs that surround the central atom. Click START on Box B to see a three-dimensional representation of a water molecule that depicts only the bonding electron pairs that surround the central atom.

grc mini grant prototype storyboard #1 lewis structure and molecular geometry

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