Summary Prediction of Molecular Geometries

chapter8-redtonfloleculo.ir Geometries
Planar relating toorintheformofa
- plane steric # → 2 [ AX ,
→ linear • m



formula and sequence
stereoisomers molecules have
the same molecular -

orientations of their coz HCN Beclz , ,


in the 3 dimensional
Of bonded atoms , but differ N


Axz

(
atoms in space → Trigonal planar
Ofa
model physical representation
graphic 5oz BF-z.NO-z.CO}
a or
-
-
m w

space filling molecular that have diameters
steric # → 3
,

partial spheres
molecule
Proportional
in which the
to those of the
atoms are
real atoms and that are joined directly to
one
gl lone pair
AXZE → bent ; bond
angle a bit less than 120° ( coulombs law ; repulsion)
another
502,03 Pbxz ,SnXz (where ✗ is a halogen)
•
w
,

where atoms
three dimensional models
ball and stick molecular model
-




are represented
- -



colors and bonds
on


represented by
are spheres of different 109.5°
→ tetrahedral bond
Axy angles of
by sticks between the spheres
silty ,CH4 SO} ,_ ,
a




having a valence of 4
cloj.TO?-,XeO4
on
tetravalent -




an


structural chemistry deals with spatial structures of molecules 11h lone pair
the
-
1
gaseous liquidor solid state> and solids (
with extended structures
that
4 A×zE trigonal pyramidal
µ
→
Steric # →
-
,


cannot be subdivided Into molecules .
.




i.e.n.s.am
"

Valence shell electron pair repulsion LVSEPR) theory
- -
-
model used -10 predict 1-130-1 Xeoz ,
a


based the number of valence shell electron
bond
3- ☐ molecular geometry on on
a

m.am#ea-...nam.....n
if 2 lone pairs
equatorial
compared
vertex
with the
-




plane
bonds to
of the
non

ring
ring
atoms that make only a small angle ..
:*
of about 900-10 the ring H2O ,
OF, SFI
angles
,
axial vertex -
bonds to non ring
atoms with µ


Plane
out


anion or molecule
attached to a metal atom by coordinate bonding a.

ligand -




Axs → Trigonal bipryamld on

X) atom (E) non bonding valence
Axm En (A) central atom ( bonded
N
-
, ,
Pclg Asfg sofa
, ,
an
and mandn are integers
alone pair of electrons )
electron group ( usually
,

a
w

fl lone pair
steric number -
Steric number-_ (number of atoms
bonded -10 central atom ) ( +
number of / one pairs
on central atom )=m+n AXyE → seesaw
" " " " ""
W
"
"
④
pyramid square pyramidal contains 2
"


halogen
IOZFÉ
Inter halogen compound square
-




steric # → 5
>
,

atoms anno atoms of elements from any other group
2 lone pairs
# f
A×zEz
•
AXSE
AXE
3 AXZEZ → 1- shaped .




IF ,BrF CIF ICI lfz Brfz Clfz IFSIBRFS GIFs ⑨
Brfz
'
, ,
, ,
CIF} , an

Brcl ,1Br
①
compound whose molecule has the same number of atoms µ

Structural isomer another
-




bonds between them
logically distinct 3 lone pairs an
.




of each element , but with


AXZE ! → linear

Stereoisomer each of two or more compounds differing only in the spatial arrangement ⑤
I} IFL
-




of their atoms
Xefz ,
,
m




or

more compounds differing only
mthe arrangement
geometric
isomers -
each of two or
bond ring or other rigid
structure Axg → octahedral
with respect -10A double , , a
of groups SFG IOFG
,
m
ar

an

kinds of atoms ,
optical isomers two
-
compounds that contain the same number and
have non
atoms but which
-
a

and bonds , and different spatial arrangements of the ,




mirror Images
super imposable
.




an




chiral -
asymmetric; structure and its mirror lmagearenotsuperimposable £1 lone pair .



seen , # → c. ⇐ → sauarepryama .
.




,µ,
.

Ifs Te -55 , ✗ e. Ofa
reaction mechanism that leads to different stereo isomeric
stereospecific property of
,
- a

different stereo isomeric reactants , or operates only one Lora
reaction products from
subset) of the stereoisomers
2 lone pairs

§¥
f
bond dipoles cancel dipole
, out ; net is zero
; molecule is nonpolar AxyE, → square planar
a

XeF4 ICI -4 as
Bfz trigonal planar
, ←




µ
a




Pclg trigonal bipryamid

Cola, tetrahedral

MO's
SF
,
octahedral AO's
orbitals
Atoms have atomic orbitals ; molecules have molecular

bond dipoles DO NOT cancel
, out ; net dipole is zero
; molecule is polar


Brfz 1- shaped Iwavel? Cloud

OF , bent


✗_-
wave
*
*
atoms interact by combining electron waves cloud 1-18,1-1
NH
,
trigonal pryamld


CO2 contains polar bonds but is not a polar molecule


bond dipoles DO NOT cancel out ; net dipole NOT zero ; molecule is polar 0--0=0 C linear )
?⃝
?⃝ , is