Summary Lone pairs and shapes of molecules

I. ONE PAIRS & SHAPE
TYPES OF BONDS
ELECTRON PAIR REPULSION THEORY
•
The shape of a molecule is determined by the covalent : shared pair of
electrons ( ≥ 1)
electron pairs surrounding the central atom .




↳ only ionic :
referring to the outer shells .

giving or
accepting
electrons between
•
Based on the fact pairs of electrons repel
metal and non -
meta

other electron pairs ( to minimise repulsion )


TRIGONAL PLANAR TETRAHEDRAL
0 ◦
double bond treated 0

120% [ ] 120°
as
single /I
µ 5 ]II / angle 109.5°
• all 120° around central 109.5° ◦
all bond
atom ''
-




0
0¥70
'




CO32
- -




0%11
◦




0
-




0 •
dative bond treated
as
regular bond
"
.




• all 120°
- .




o
1 EFFECTS OF LONE PAIRS
dative bond .

The extra repulsion decreases all bond

angles by 2.5°
TRIGONAL B/ PYRAMIDAL lone pair
in
three bonding
-



CI
""
H -
Ñ -
H
pairs

jf%fp bonding pairs lone pair
-




fine one
- .




, µ ,
-

bond angle 90° to
107° H 107° -
based on tetrahedral
} 90
/ g• Cl
atoms above / below ↳ pyramidal , 109-5-2.5

a
-
bond angle 120° to
= 107°
atoms on planar / =
trigonal

OCTAHEDRAL -

two lone pairs
:O
.



two
bonding pairs
-
.




F F It 109-5-(2.5×2)=104.50
F%%
H
six bonding pairs
-
-
.




-
all bond angles
-
V
-


shaped / bent
90° < ( on the central plane .



And tag above and below)

F 90°
F F are .