Download Worksheet for Week 3 Recitation

Worksheet for Week 3 Recitation Notes
For each of the following molecules/ions:
1.
2.
3.
4.
5.
Determine the Lewis dot structure
(give resonance structures if applicable)
Determine the molecule geometry
Determine the bond angles
Identify the bonds as polar or non-polar
Identify the molecule/ion as polar or non-polar
Methane
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—tetrahedral; the four pairs of electrons around
the central atom are oriented as far away from one-another.
3.
Determine the bond angles—109.5 º
4.
Identify the bonds as polar or non-polar—all four bonds are polar; not very polar,
the difference between the electronegativity of carbon and hydrogen are slight.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
C-H bonds are in "equal and opposite directions.
Ethane
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—tetrahedral about each carbon
3.
Determine the bond angles—109.5 º
4.
Identify the bonds as polar or non-polar—all six C-H bonds are polar; not very
polar, the difference between the electronegativity of carbon and hydrogen are
slight. The C-C bond is non-polar.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
C-H bonds are in "equal and opposite directions.
Ethene
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—trigonal planar about each carbon
3.
Determine the bond angles—120 º
4.
Identify the bonds as polar or non-polar—all four C-H bonds are polar; not very
polar, the difference between the electronegativity of carbon and hydrogen are
slight. The C=C bond is non-polar.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
C-H bonds are in "equal and opposite directions.
Ethyne
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—linear
3.
Determine the bond angles—180 º
4.
Identify the bonds as polar or non-polar—both C-H bonds are polar; not very
polar, the difference between the electronegativity of carbon and hydrogen are
slight. The C-C bond "triple" is non-polar.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
C-H bonds are in "equal and opposite directions.
Propane
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—tetrahedral about each carbon
3.
Determine the bond angles—109.5 º
4.
Identify the bonds as polar or non-polar—all C-H bonds are polar; not very polar,
the difference between the electronegativity of carbon and hydrogen are slight.
The C-C bonds are non-polar.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
C-H bonds are in "equal and opposite directions.
Tetrafluoromethane (CF4)
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—tetrahedral; the four pairs of electrons around
the central atom are oriented as far away from one-another.
3.
Determine the bond angles—109.5 º
4.
Identify the bonds as polar or non-polar—all four bonds are polar; very polar, the
difference between the electronegativity of carbon and fluorine is large: 2.5 and
4.0.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
C-F bonds are in "equal and opposite directions.
Water
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—bent; the four pairs of electrons around the
central atom are oriented as far away from one-another.
3.
Determine the bond angles—109.5 º (actually, a little less than 109.5 º because of
the lone pairs of electrons on the oxygen).
4.
Identify the bonds as polar or non-polar—both bonds are polar; very polar, the
difference between the electronegativity of oxygen and hydrogen is large: 3.5 and
2.1.
5.
Identify the molecule/ion as polar or non-polar—polar; good symmetry left to
right, but their is a dipole top to bottom.
BH3
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—trigonal planar
3.
Determine the bond angles—120 º
4.
Identify the bonds as polar or non-polar—all three B-H bonds are slightly polar;
not very polar, the difference between the electronegativity of boron and
hydrogen is very slight 2.0 and 2.0.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
B-H bonds are in "equal and opposite directions.
NO31.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—trigonal planar
3.
Determine the bond angles—120 º
4.
Identify the bonds as polar or non-polar—all three N-O bonds are polar; the
difference between the electronegativity of nitrogen and oxygen is 3.0 and 3.5.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
N-O bonds are in "equal and opposite directions.
Special note: The N-O bond order is 1.33 (4 bonds over 3 locations).
CO321.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—trigonal planar
3.
Determine the bond angles—120 º
4.
Identify the bonds as polar or non-polar—all three C-O bonds are polar; the
difference between the electronegativity of carbon and oxygen is 2.5 and 3.5.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
C-O bonds are in "equal and opposite directions.
Special note: The C-O bond order is 1.33 (4 bonds over 3 locations).
CH3COOH / CH3COO1.
Determine the Lewis dot structure
(give resonance structures if applicable)
On the left is the Lewis dot structure for acetic acid (CH3COOH)
On the right is the Lewis dot structure for acetate ion (CH3COO-)
Acetate resonance forms:
2.
Determine the molecule geometry
Tetrahedral about the carbon on the left
Trigonal planar about the carbon on the right
Bent about the lower oxygen in acetic acid
3.
Determine the bond angles—109.5 º (about left carbon); 120 º (about the right
carbon), and near 109.5 º (about the lower oxygen in acetic acid)
4.
Identify the bonds as polar or non-polar—all bonds are polar except the C-C
bond.
5.
Identify the molecule/ion as polar or non-polar—both are polar; draw the arrows
from left to right
NH3
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—trigonal pyramidal. The electron pairs are
arranged tetrahedral, but the molecular geometry is trigonal pyramidal; the four
pairs of electrons around the central atom are oriented as far away from oneanother.
3.
Determine the bond angles—near 109.5 º
4.
Identify the bonds as polar or non-polar—all three bonds are polar; the difference
between the electronegativity of nitrogen and hydrogen is 3.0 and 2.1.
5.
Identify the molecule/ion as polar or non-polar—polar; nice symmetry "left to
right," but the top is not the same as the bottom. Draw an arrow from bottom to
top.
PH3
Same as NH3.
PCl3
Same as PH3 and NH3.
PCl5
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—trigonal bipyramidal. The five pairs of
electrons around the central atom are oriented as far away from one-another.
3.
Determine the bond angles—120 º and 90 º
4.
Identify the bonds as polar or non-polar—all five bonds are polar; the difference
between the electronegativity of P and Cl is 2.1 and 3.0.
5.
Identify the molecule/ion as polar or non-polar—non-polar; nice symmetry.
SF6
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—octahedral. The six pairs of electrons around
the central atom are oriented as far away from one-another.
3.
Determine the bond angles—90 º
4.
Identify the bonds as polar or non-polar—all five bonds are polar; the difference
between the electronegativity of S and F is 2.5 and 4.0.
5.
Identify the molecule/ion as polar or non-polar—non-polar; nice symmetry.
XeF2
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—linear. The five pairs of electrons around the
central atom are oriented as far away from one-another.
3.
Determine the bond angles—180 º
4.
Identify the bonds as polar or non-polar—both bonds are polar; the difference
between the electronegativity of F and Xe is 4.0 and "not 4.0."
5.
Identify the molecule/ion as polar or non-polar—non-polar; nice symmetry.
XeF4
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—square planar. The six pairs of electrons
around the central atom are oriented as far away from one-another.
3.
Determine the bond angles—90 º
4.
Identify the bonds as polar or non-polar—all four bonds are polar; the difference
between the electronegativity of F and Xe is 4.0 and "not 4.0."
5.
Identify the molecule/ion as polar or non-polar—non-polar; nice symmetry.
Ozone (O3)
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—bent; the three groups of electrons around the
central atom are oriented as far away from one-another.
3.
Determine the bond angles—about 120 º
4.
Identify the bonds as polar or non-polar—non-polar.
5.
Identify the molecule/ion as polar or non-polar— while the two bonds are not
polar, there is an "unbalanced" pair of electrons atop the central.
Ammonium ion (NH4+)
1.
Determine the Lewis dot structure
(give resonance structures if applicable)
2.
Determine the molecule geometry—tetrahedral; the four pairs of electrons around
the central atom are oriented as far away from one-another.
3.
Determine the bond angles—109.5 º
4.
Identify the bonds as polar or non-polar—all four bonds are polar; the difference
between the electronegativity of N and H is 3.0 and 2.1.
5.
Identify the molecule/ion as polar or non-polar—non polar; high symmetry—the
N-H bonds are in "equal and opposite directions.