5. STRUCTURE OF NH3
Ammonia molecule is
trigonal pyramidal with
the nitrogen at the apex.
The N atom in NH4 is sp
hybridized containing
lone pair of electrons
due to which the bond
angle. H-N-H is 107.5 .It
has three bond pairs and
one lone pair of
electrons.
3
o
. .
N
H H
H
107.5
o
7. DINITROGEN OXIDE: N2O
:N = N
= O :
..
..
N = N = O
..
..
..
..
It is known as laughing gas because it
produces hysterical laughter. It is
diamagnetic linear molecule
8. NITRIC OXIDE (Nitrogen Monoxide)
:N = O:
_
.. .
+
:N = O:
. ..
(IONIC STRUTURE)
N-O = 115 pm.
(COVALENT STRUCTURE)
……………………………
…….
…….
……………………………
N
O
O
N
Covalent structure
Dimeric
structure
Of NO
It is an oxidizing as well as reducing agent. It is the most stable oxide
of nitrogen. It is odd electron (11 valence electrons) molecule and
paramagnetic in gaseous state. However , in solid or in liquid state,
it exists as dimer and hence is diamagnetic. NO molecule has one
unpaired electron which may be on nitrogen or oxygen.
11. DINITROGEN TETRAOXIDE: N2O4
..
:O:
N
O
..
..
N
:O:
..
O
..
.. :O
:O:
N N
:O:
..
.. O
..
..
O
O
N
O
N
O
176 pm
118 pm
135
o
It is an acidic oxide, in equilibrium with NO2 in gas phase. N2O4 molecule has no
unpaired electron hence it is diamagnetic. N atom has one unpaired electron, in
NO2 molecule is formed by dimerisation of two NO2 molecules. The N-N bond is
formed by two unpaired electrons in two sp hybrid orbitals of two N atoms. It is a
planar molecule.
3
13. STRUCTURE OF PCl3
. .
P
Cl
Cl
Cl
In PCl3, the phosphorus
undergoes sp hybridization
and carries lone pair of
electrons. It has pyramidal
shape.
3
14. STRUCTURE OF PCl5
240
pm
p
Cl
Cl
Cl
Cl
Cl
Bipyramidal structure of PCl5
PCl5 in gaseous and liquid phase possesses trigonal bipyramidal structure. The
central p-atom in it undergoes sp d hybridization. There are total 5 bonds. The
three equatorial P-Cl bonds are equivalent, while two axial bonds are longer than
equatorial bonds. It is due to the fact that the axial bond pairs suffer more
repulsion as compared to equatorial bond pairs. X-ray studies showed that in solid
state it has the structure [PCl6] [PCl4] .PCl5 is not stable due to its unsymmetrical
shape, where some bond angle are 90 and are of 120 .
+
_
3
16. Hypophosphorus Acid (H3PO2)
P
O
H H
H
Hypophosphorus (Phosphinic) acid:
(H3PO2) Oxidation state of phosphorus
is +1. It consists of P=O. Phosphorus on
n=boiling with Ba(OH)2 gives
Ba(H2PO2)2 preciptate. It I filtered and
sulphuric acid is added to get free
hypophosphorus acid.
3Ba(OH)2 + 8P + 6H2O 3Ba(H2PO2)2 + 2PH3 ppt
Ba(H2PO2)2 + H2SO4 BaSO4 + 2H3PO2 ppt
17. Orthophosphorus Acid (H3PO3)
O
P
H OH
OH
Orthophosphorus (Phosphonic) acid.
(H3PO3): Oxidation state +3. It contain
two P-OH bond. It is obtained by action
of water on P2O3. It is a dibasic acid. In
alkaline solution the acid and its salts
are reducing agents. Gold , silver and
copper are precipitated from their salt
solution by orthophosphorus acid.
P4O6 +6H2O 4H3PO3
18. Pyrophosphorus Acid (H4P2O5)
O
P O P
O
OH OH
H H
Phosphorus acid (H4P2O6):
Oxidation state of
phosphorus is +3. It
consists of two P-OH
bonds, two P-H and two
P=O bonds. It also
contains one P-O-P bond.
It is obtained by reaction
between PCl3 and H3PO3. It
is a dibasic acid.
19. Hypophosphoric Acid (H4P2O6)
O
P
OH
OH P
O
OH
OH
Hypophosphoric acid (H4P2O6):
Oxidation state of phosphorus is +4.
It contains four P-OH bonds, two
P=O bonds and one P-P bond.
Reaction between red phosphorus
and alkali gives this acid.
It decomposes on heating to form
phosphorus acid and
metaphosphoric acid.
H4P2O6 H3PO3 + HPO3
20. Orthophosphoric Acid (H3PO4)
O
P
OH OH
OH
Orthophosphoric acid (H3PO4):
Oxidation state of phosphorus in H3PO4
is +5. It consists of three P-OH bonds, one
P=O bond. It is prepared by reaction
between P4O10 and water and
manufactured from bone ash.
P4O10 + 6H2O 4H3PO4
21. Pyrophosphoric Acid (H4P2O7)
O
P
OH O
OH
O
P
OH
OH
Pyrophosphoric acid (H4P2O7):
Oxidation state of phosphorus in this
compound is +5. For n=3, it consists of
three P-OH bonds, two P=O bonds and
two P-O-P bond. It is obtained by simply
heating H3PO4. On boiling with water it
slowly changes to ortho phosphoric acid.
2H3PO4 H4P2O7 + H2O
H4P2O7 + H2O 2H3PO4
22. Polymetaphosphoric Acid (HPO3)n
O
P
O
OH
O
P
O O
OH
OH
P
O
O
Polymetaphosphoric acid
(HPO3)n: The oxidation state of
phosphorus is +5. For n=3, it
consists of three P-OH bonds,
three P=O bonds and two P-O-P
bonds. It is prepared by heating
a mixture of phosphorus acid
and Br2 in a sealed tube.
It exists in polymeric form only. It is also called glacial phosphoric acid. The acids
which contain P-H bonds have strong reducing tendency. The hypophosphorus acid
which contain two P-H bonds reduces AgNO3 to metallic silver. These P-H bonds in
oxoacids of phosphorus do not ionise to give H ions do not show any basicity. Only
those H atoms which are attached with oxygen in P-OH form ionize and cause
basicity. Thus H3PO3 is a dibasic acid since it contains two P-OH bonds. H3PO4 is a
tribasic acid since it contain 3 P-OH bonds.
4AgNO3 + 2H2O +H3PO2 4Ag + 4HNO3 + H3PO4
23. STRUCTURE OF SULPHUR
S S S
S
S
S
S
S
107
o
Crown shaped puckered ring of S8
S S
S S
S
S
Chair structure of sulphur
S
S
S
S
S
S
S
S
Open chain S8 molecule
24. STRUCTURE OF OZONE
O
..
O
..
O
O
O 117
O
Resonating structures of ozone
Infrared and electron diffraction spectra show that
ozone molecule is angular with O-O-O bond angle as
117 . Both O-O bonds are identical having bond
length 128pm which is intermediate between single
and double bonds. It is a resonance hybrid of two
structures.
O
25. Oxoacids of sulphur
H-O-S-OH
Sulphoxylic acid H2SO2
S
S
..
HO OH
Thiosulphurous acid H2S2O2
O
S
HO OH
O
S
O
S
..
HO OH
Sulphurous acid H2SO3
Dithionous acid H2S2O4
O
S
HO OH
O
S
O
Pyrosulphurous acid or disulphurous acid
O
S
HO OH
O
Sulphuric acid H2SO4
26. S
S
HO OH
O
Thiosulphuric acid H2S2O3 Pyrosulphuric acid or oleum H2S2O7
OH
O
S
O
O
HO
Peroxy monosulphuric acid H2SO5
O
S
HO
O
OH
O
S
O
O
O
S
HO
O
O OH
O
S
O
O
Peroxy disulphuric acid H2S2O8
O
S
HO
O
OH
O
S
O
Dithionic acid H2S2O6
27. Oxyacids of chlorine
O
..
..
H Cl:
..
..
HOCl HOClO
H Cl:
..
..
O
..
..
Cl
:O:
H
HOClO3
Cl
:O:
H
HOClO4
Oxidation power of these oxyacids decreases as the oxidation number of halogen
increases
HClO > HClO2 > HClO3 > HClO4
Thermal stability increases with increase in oxidation state of halogen
HOClO > HOClO > HOClO2 > HOClO3
