Activity - Molecule polarity demonstration-1 PDF

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Molecule Polarity Simulation Visit the Molecule Polarity simulator. 1. Select the “Real Molecules” simulation option (click on the “Real Molecules Only in Java” link; you will then be prompted to download the simulation). Once you download the simulation to your device, open the simulation and begin the activity. Set 1: HF vs. H2 For each molecule be sure to have the “Atom Labels” and “Atom Electronegativies” button selected. Use the “Bond Dipoles” and “Molecular Dipoles” buttons to determine if these dipoles are present when instructed below. (a) Use the simulation to determine if bond dipoles are present on each molecule. (b) Use the simulation to determine if a molecular dipole is present on each molecule. (c) Use the simulation “Electrostatic Potential” option to map the electron density on each molecule. Molecule

H2

Electronegativit y Difference between atoms 2.1 – 2.1 = 0

Bond Dipoles Molecular Present? Dipole Present? (yes or no) (yes or no) no no

HF

4.0 – 2.1 = 1.9

yes

Sketch/describe the Electrostatic Potential

yes

Question 1: Using what you learned from Set 1, predict what properties of the molecule determine if a molecular dipole is present or not. - Molecules with non-polar bonds will be non-polar. Molecules with polar bonds might be polar. Set 2: Repeat the data collection carried out in Set 1 for each set molecules below. Be sure to have the “Atom Labels” “Atom Electronegativies” button selected. Use the “Bond Dipoles” and “Molecular Dipoles” buttons to determine if these dipoles are present when instructed below. (a) Use the simulation to determine if bond dipoles are present on each molecule. (b) Use the simulation to determine if a molecular dipole is present on each molecule. (c) Use the simulation “Electrostatic Potential” option to map the electron density on each molecule. Molecul e BF3

Electronegativit y Difference between atoms 4.0 – 2.0 = 2.0

Bond Dipoles Molecular Present? Dipole Present? (yes or no) (yes or no) Yes No

Sketch/describe the Electrostatic Potential

NH3

3.0 – 2.1 = 0.9

Yes

Molecul e H2O

Electronegativit y Difference between atoms 3.5 – 2.1 = 1.4

Bond Dipoles Molecular Present? Dipole Present? (yes or no) (yes or no) Yes Yes

CO2

3.5 – 2.5 = 1.0

Yes

No

Molecul e

Electronegativit y Difference between atoms 2.5 – 2.1 – 0.4

Bond Dipoles Present? (yes or no) Yes

Molecular Dipole Present? (yes or no) No

CH3F

C-H 2.5 – 2.1 = 0.4 C-F 4.0 – 2.5 = 1.5

Yes

Yes

Molecul e H2O

Electronegativit y Difference between atoms 3.5 – 2.1 = 1.4

Bond Dipoles Molecular Present? Dipole Present? (yes or no) (yes or no) Yes Yes

NH3

3.0 – 2.1 = 0.9

Yes

Molecul e

Electronegativit y Difference between atoms C-H 2.5 – 2.1 = 0.4 C-F 4.0 – 2.5 = 1.5 C-H 2.5 – 2.1 = 0.4 C-F 4.0 – 2.5 = 1.5

Bond Dipoles Molecular Present? Dipole Present? (yes or no) (yes or no) Yes Yes

CH4

CH3F

CHF3

Yes

Yes Sketch/describe the Electrostatic Potential

Sketch/describe the Electrostatic Potential

Sketch/describe the Electrostatic Potential

Yes

Sketch/describe the Electrostatic Potential

Yes

Analyze and Evaluate: (a) Compare the molecules that have a net molecular dipole and those that do not. What are the common features for the molecules that have net molecular dipoles? - Molecules with net dipoles have polar bonds and asymmetrical shapes.

(b) Compare the molecules that have a net molecular dipole and those that do not. What are the common features for the molecules that DO NOT have net molecular dipoles? - Molecules with no net dipoles either have non-polar bonds, or have polar bonds and symmetrical shapes. (c) Create a general statement that summarizes how you can predict if a molecule will polar or not (i.e., create a statement that begins “A molecule will have a net molecular dipole if…”). - A molecule will have a net molecular dipole if it has polar bonds and a VSEPR shape that is asymmetrical....