icl 4 –
DESCRIPTION
. [ ]. –. Cl–. –Cl. I. Cl. H. O. H. H–C–C–O–H. Cl. –. C=O. –. –OH. ICl 4 –. EDG: octahedral. MG: sq. planar. 36 e –. For molecules with more than one central atom, simply apply the VSEPR model to each part. Predict the EDG and MG around the three interior - PowerPoint PPT PresentationTRANSCRIPT
ICl4–
36 e–
EDG: octahedralMG: sq. planar[ ]
..
I–ClCl–....
..
....
....
....
Cl
Cl
..
..
....
–
For molecules with more than one central atom,simply apply the VSEPR model to each part.
Predict the EDG and MG around the three interioratoms of ethanoic (acetic) acid.
H–C–C–O–H..H
..H O....
CH3COOH PORTION EDG MG
tetra. tetra.–CH3
trig. plan. trig. plan.
tetra. bent
C=O–– ..
..–OH
..
..
Nonbonding domains are attracted to only one nucleus;therefore, they are more spread out than are bondingdomains. The effect is that nonbonding domains(i.e., “lone pairs”) compress bond angles. Domains formultiple bonds have a similar effect.
e.g.,
CH4 NH3 H2O
NHH
H
..
CHH
H
H OH
..
H
..
..ClO=C
Cl......
....
....
the ideal bond angle for the tetrahedralEDG is 109.5o
111.4o
EDG = trig. plan.ideal = 120o
COCl2
124.3o
124.3o
109.5o107.0o 104.5o
Polarity of Molecules
A molecule’s polarity is determined by its overalldipole, which is the vector sum of the dipoles ofeach of the molecule’s bonds.
Consider CO2 v. H2S...
O=C=O....
.... S
H
..
H
..bond dipoles
overall dipole =
bond dipoles
overall dipole =
(NONPOLAR) (POLAR)
zero
Boron can be extracted bythe electrolysis of moltenboron trichloride. Boron isan essential nutrient forplants, and is also a primarycomponent of control rodsin nuclear reactors.
Classify as polar or nonpolar:
PCl3
BCl3
26 e–
P–ClCl–....
..
....
....
....Cl
..polar
..
B–ClCl–..
.. .... ....
Cl .... nonpolar
24 e–
Valence-Bond Theory: merges Lewis structures w/the idea of atomic orbitals (2s, 3p, etc.)
V-B theory says… covalent bonding occurs whenvalence orbitals of adjacentatoms overlap; then, two e–sof opposite spin (one fromeach atom) combine to forma bond
Lewis theory says… covalent bonding occurs whenatoms share electrons
V-B theory is like Velcro: “No overlap, no bond.”
Consider H2, Cl2, and HCl...
H
Cl [Ne]
H2 Cl2
HCl
(unpaired e– is in 1s orb.)
(unpaired e– is in 3p orb.)
= orbital overlap region (responsible for bond)
There is always an optimum distance between twobonded nuclei. At this optimum distance, attractive (+/–) and repulsive (+/+ and –/–) forcesbalance.
H–H distance
Energy
0
optimum dist.(min. PE)
H2 molecule