Chemical Bonding and Structure Summary

'
Bond length distance between atoms when bonded

Bond amount of energy released when
energy
•
=


°
bona is formed an

§Ñ
distance between nuclei

→
Energy supplied to BREAK bond
→
Energy released to FORM new bond .




Atoms bond to become
more STABLE Bond strength strength
: of attraction
→
shorter bond length =
stronger bond
→
smaller atoms =
stronger bond

more bonds stronger bond
→
=




chemical bonding
0
Bonds = forces of attraction : hold atoms together .




Bonding gain stability [octet / noble gas]
0 =




1. Covalent bonds :
A sharing of at least one pair of electrons by two non -
metals


°
Diatomic molecules =
atoms from same element E. H2
g
°
molecules =
atoms from different elements



Electronegativity :
A measure of the tendency of an atom to attract a bonding pair of electrons .




Polar covalent bond :
An intramolecular bond that arises due to unequal sharing of electrons leading to a dipole forming
as a result of electronegativity difference .




→
EN 1=0

Different atoms
→




→
e- not shared equally :
shift to higher EN ( has stronger force)
→

charges develop =
dipole formed


Non polar covalent bond An intramolecular bond that arises due
-
: to equal sharing of electrons .




→
EN =
0
diatomic molecules
→



→
e- shared
equally
→
No charges developed .




Polarity of MOLECULE using charge distribution .




Non -


polar molecule : even distribution (no poles) E.g. CH4


Polar molecule :
uneven distribution ( poles) E.g HC1

, Steps to follow


I. Central atom { valence e-

2. Lone pairs of e-

3.
Shape
4. Bond polarity
5. Molecule polarity NOTE !
☐

valency = # of e- to be accepted / donated
tg.HU # of
• valence e- =
outermost electrons
↳
I. Group # valence e- valency # of bonds group # =
# of valence e-

Hydrogen 1 I 1 1

Chlorine 7 7 8-7=1 I




2 .
No central atom or lone pairs

3. :
linear


4 .



g- < I
gt
i.
polar covalent bond

a- It
EN 3,0
__
EN -2,1 -




Sgt , > 8-
H -
'


II :

/ °




i.
polar molecule


1-
g. C02 # of
1 . Group # valence e- valency # of bonds
Types of shapes
carbon 4 4 8-4=4 4

Oxygen 6 6 8-6=2 2 '



Linear


2. Carbon
2 lone
central

pairs on
atom

each oxygen atom .
-


Tetrahedral
o¥o
A
Pyramidal
.



3 . .




0 :C :O 650
.




linear
. ' '
.




4.
g- 1 ft a :
polar covalent bond
O=c
EN -3,0 -
EN -2,5



s . 50=6 g-
i.
non -


polar molecule