LAB 3 Molecular Geomtery PDF

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Mohammad Alhilal

CHEMISTRY 1110L LAB 3 MOLECULAR GEOMETRY Submit this table filled out for grading. Note: for geometries derived from the trigonal bi-pyramidal electron domain geometry there will be two bond angles, you need to list them both.

BF3 SO2 CH4

Real molecule Polar or non-polar Non-polar Polar Non-polar

Real molecule bond angle(s) 120° 119° 109.5°

Model Molecule bond angle(s) 120º 120° 109.5°

NH3

Polar

107.8°

109.5°

H2O Pcl5

Polar Polar

104.5° 90°, 120°

109.5° 90°, 120°

1

Trigonal Pyramidal Bent Trigonal bipyramidal Seesaw

SF4

Polar

2

T-Shaped

ClF3

Polar

90°, 120° 90°, 90°

3

Linear

XeF2

Non-polar

87.8°, 101.6° 87.5°,87.5 ° 180°

0 1 2

Octahedral SF6 Square Pyramidal BrF5 Square Planar XeF4

Non-polar Polar Non-polar

90° 89.5° 90°

90° 90° 90°

Electron Domain Lone pair geometry electron s Trigonal planar 0 Trigonal Planar 1 Tetrahedral 0

Molecular geometry

Real molecule

Trigonal Planar Bent Tetrahedral

Tetrahedral

1

Tetrahedral Trigonal bipyramidal Trigonal bipyramidal Trigonal bipyramidal Trigonal bipyramidal Octahedral Octahedral Octahedral

2 0

1

180°

Part 1b) Bond angles are not the same between real molecules and model molecules for several cases. Do you notice a trend? What does it appear that the model is NOT taking into account? (explain)

Yes, Bond angle is not same between real and model molecules. It happens due to the presence of lone pairs on the atoms and due to the forces exerted due to them the geometry gets distorted and it is causing a change in the expected geometry. The model is not taking into consideration the effects of the presence of lone pairs.

Part 2: For each molecule or polyatomic ion listed below, write a Lewis Structure, predicted VSEPR geometry and name for each compound. 1) ClF3 Name : Chlorine Trifluoride VSEPR geometry : trigonal bipyramidal Lewis structure :

2) CO32Name : Carbonate Ions 2

VSEPR geometry: trigonal-planar Lewis structure:

3) BrF5 Name: Bromine Pentafluoride VSEPR geometry : square pyramidal Lewis structure:

4) XeF4 Name : Xenon Tetrafluoride VSEPR geometry : Square planar Lewis structure:

3

5) NO3Name : Nitrate ion VSEPR geometry: Trigonal Planar Lewis structure:

6) CS2 Name : Carbon disulfide VSEPR geometry : linear Lewis structure

4

7) SbCl5 Name : Antimony pentachloride VSEPR geometry : Trigonal bipyramidal Lewis structure:

8) AlI3 Name : Aluminium iodide VSEPR geometry : trigonal planar Lewis Structure:

Part 3 Build a hypothetical molecule with a central atom A surrounded by 3 hydrogen atoms and one additional atom X. The formula for this compound is AH3X. 5

Atom A has an electronegativity = 2.4 and 4 valence electrons. Atom X has an electronegativity of 3.2 and has 7 valence electrons. a) Write a Lewis Structure for AH3X

b) What is the electron domain geometry of the molecule? As there is no lone pairs present on the central atom. So, it is of the form of AB4. The electron domain geometry would be Tetrahedral.

c) What is the molecular geometry of this molecule? Tetrahedral. d) Is the molecule polar or non-polar? The A-H bond is considered nonpolar; thus, no dipole. But the A-Cl bond is polar, the AH3X has a net dipole, so AH3X is polar.

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