The Representative Elements: Groups 5A Through 8A Chapter 19.
21
The Representative The Representative Elements: Elements: Groups 5A Through 8A Groups 5A Through 8A Chapter 19
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Transcript of The Representative Elements: Groups 5A Through 8A Chapter 19.
The Representative Elements:The Representative Elements:Groups 5A Through 8AGroups 5A Through 8A
Chapter 19
19_404MoleculeType
Molecularstructure
Hybridizationof M
MX3
MX5
MX6
Pyramidal
Trigonalbipyramidal
Octahedral
MX
XX
M
X
X
XX
X
X
X
X
XX
XM
M
Lone pair
sp3
M
M
dsp3
d2sp3
Types of molecules formed by Group VA elements.
NitrogenNitrogen
The great stability of the NN bond means that most binary compounds containing nitrogen decompose exothermically to the elements.
NO2(g) 1/2N2(g) + O2(g) H = 34 kJ
N2H4(g) N2(g) + 2H2(g) H = 95 kJ
Nitrogen FixationNitrogen Fixation
. . . the process of transforming N2 to other nitrogen-containing compounds.
The Haber Process
N2(g) + 3H2(g) 2NH3(g) H = 92 kJ
P = 250 atm
T = 400C
19_406
Unr
eac
ted
N2,
H2
ImpureN2, H2
Unwanted tracegases removed
PureN2, H2
Catalyticreactors
NH3
Coolingchamber
Liquid NH3
(yield 20%on eachcycle)
Schematic diagram of the Haber Process for the maufactureof ammonia.
19_407
NitratesPlant andanimalprotein
Ammonia Nitrites
N2 in the atmosphere
N-fixingbacteria
Bacteria
BacteriaDecayprocesses
Denitrifyingbacteria
Lightning
The nitrogen cycle. To be used by plants and animals, nitrogenmust be converted from N2 to nitrogen-containing compounds.
Nitrogen HydridesNitrogen Hydrides
Ammonia, NH3
Hydrazine, N2H4
Monomethylhydrazine, N2H3(CH3)
Nitrogen OxidesNitrogen Oxides
Compound Oxidation State of N
N2O +1
NO +2
N2O3 +3
NO2 +4
HNO3 +5
Nitrogen in its oxides has an oxidation state Nitrogen in its oxides has an oxidation state from +1 to +5from +1 to +5
19_410
NO
byp
rodu
ct
NH3
Oxidation at900C withPt – Rh catalyst
NO
Oxidation withO2 at 25 C
NO2
Dissolvedin H2O
HNO3
Schematic for the production of HNO3 by the Ostwald Process.
Allotropes of Phosphorus - PAllotropes of Phosphorus - P44
- White Phosphorus (WP) = tetrahedra - very reactive
- Black Phosphorus (BP) = crystalline structure much less reactive
- Red Phosphorus (RP) = amorphous with P4 chains.
WP RP
WP or RP BP
heat atm no air
high pressure
, ,1
19_412
(a) (b)
(c)
a) the P4 molecule. b) crystalline network structure of blackphosphorus c) chain structure of red phosphorus.
19_413
P
P PP
P
P
PP
O
OO
O
OO
P
P
PP
O
OO
O
OO
O
O
O
O
LimitedO2
ExcessO2
P4O6 P4O10
The structure of P4O6 and P4O10.
19_415
H
H
H
O
P O
H
H
H
O
P OO
(a) (b)
The structure of phosphorous acid and hypophosphorous acid.
19_416
(a) (b)
X
P
X
X
X
XP X
X
X
a) Structure of PX3 compounds. b) Structure of PX5 compounds.
19_418
Air
Superheatedwater
Moltensulfur
Moltensulfur
The Frasch Method for recovering sulfur from undergrounddeposits.
OzoneOzone
OO
O OO
O
3O3O22((gg) ) 2O 2O33((gg) ) KK 10 105757
Sulfur Oxide ReactionsSulfur Oxide Reactions
2SO2(g) + O2(g) 2SO3(g)
SO2(g) + H2O(l) H2SO3(aq)
SO3(g) + H2O(l) H2SO4(aq)
Preparation of Hydrogen Preparation of Hydrogen HalidesHalides
H2(g) + X2(g) 2HX(g)
OR
Treating halide salts with acid:
CaF2(s) + H2SO4(aq) CaSO4(s) + 2HF(g)
2NaCl(s) + H2SO4(aq) Na2SO4(s) + 2HCl(g)
19_426
Hypochlorite ion,OCl
Chlorate ion,ClO3
Chlorite ion, ClO2 Perchlorate ion, ClO4
Cl O
The structures of the oxychloro anions.
Noble GasesNoble Gases
He, Ne and Ar form no compounds.
Kr and Xe have been observed to form chemical compounds:
Xe(g) + 2F2(g) XeF4(s) [6 atm, 400C]
XeF6(s) + 3H2O(l) XeO3(aq) + 6HF(aq)
19_429
F
Xe
F
F
Xe
F
O
O
F
Xe
FO
O
O
OO
O
Xe XeO
O
O
O
F
F
Xe
F
F F
F
Xe
F
F
O
O
XeF2Linear
XeO2F2Distorted tetrahedron
XeO3Pyramidal
XeO4Tetrahedral
XeO2F4Octahedral
XeO3F2Trigonal bipyramid
XeF4Square planar
The structure of several known xenon compounds.
