Transcript ch19

The Representative
Elements: Group 5A
Through 8A
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19a–2
Figure 19.1: Pyramidal shape of the
Group 5A MX3 molecules
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19a–3
Figure 19.2: Trigonal bipyramidal shape of
the MX5 molecules
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19a–4
Figure 19.3: Octahedral PF6-
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19a–5
Figure 19.4: Structures of the tetrahedral
MX4+ and the octahedral MX6- ions
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19a–6
Figure 19.5: Inert atmosphere box
Source: Corbis
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19a–7
Properties of Nitrogen
Atomic Number
Density (g/L)
Melting Point (oC)
Boiling Point (oC)
Atomic Radius (pm)
Ionic Radius, N-3 (pm)
Electronegativity
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7
1.25
-210
-196
74
171
3.0
19a–8
How Air Bags Work
In an accident, sensors initiate the reaction with a spark
2NaN3(s) => 2Na(s) + 3N2(g)
reactive sodium destroyed by
10Na(s) + 2KNO3(s) => K2O(s) + 5Na2O(s) + N2(s)
heat converts hazardous products into glass
K2O(s) + Na2O(s) + SiO2(s)heat
=> glass
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19a–9
Ostwald Process: Nitric Acid
4 NH3(g) + 5 O2(g) => 4 NO(g) + 6 H2O(g)
2 NO(g) + O2(g) => 2 NO2(g)
3 NO2(g) + H2O(l) => 2 HNO3(aq) + NO(g)
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Figure 19.6:
Schematic
diagram of
the Haber
process for
the
manufacture
of ammonia.
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19a–11
Figure 19.7: Nitrogen cycle
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19a–12
Nitrogen Cycle
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19a–13
Nodules on the roots of pea plants contain
nitrogen-fixing bacteria.
Source: Photo Researchers, Inc.
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19a–14
Figure 19.8: Molecular structure of
hydrazine (N2H4)
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19a–15
Blowing agents--such as hydrazine, which forms nitrogen
gas on decomposition--are used to produce porous plastics
like these polystyrene products.
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19a–16
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19a–17
Copper penny
reacts with nitric
acid to produce
NO gas, which
is immediately
oxidized in air to
give reddish
brown NO2-.
Source: Fundamental
Photographs
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19a–18
Figure 19.9: Molecular orbital energy-level
diagram for nitric oxide (NO).
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19a–19
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19a–20
Kissing bug
Source: Photo Researchers, Inc.
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19a–21
Three-dimensional complex nitrohphorin-1
Source: Department of Biochemistry, University of Arizona, Tuscon
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19a–22
Properties of Phosphorus
Atomic Number
Density (g/L)
Melting Point (oC)
Boiling Point (oC)
Atomic Radius (pm)
Ionic Radius, P-1 (pm)
Electronegativity
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15
1.82
44
280
110
212
2.1
19a–23
Phosphate Fertilizers
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19a–24
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19a–25
Isolation of P
2Ca3(PO4)2 +6SiO2 +10C (1500°C)
6CaSiO3
+ 10CO + P4
The reaction may proceed via "phosphorus
pentoxide", P4O10
2Ca3(PO4)2 + 6SiO2
P4O10 + 10C
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6CaSiO3 + P4O10
10CO + P4
19a–26
磷
•used in the manufacture of safety matches, pyrotechnics, incendiary
shells, smoke bombs, tracer bullets, etc.
•Fertilisers(肥料)
•phosphates are used in the production of special glasses, such as
those used for sodium lamps
•bone-ash, calcium phosphate, is used to produce fine chinaware and
to produce monocalcium phosphate used in baking powder
•important in the production of steels, phosphor bronze, and many
other products
•Na3PO4 is important as a cleaning agent, as a water softener, and for
preventing boiler scale and corrosion of pipes and boiler tubes
•pesticides (殺蟲劑)
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19a–27
磷循環
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19a–28
FeAsS (700°C)
FeS + As(g)
As(s)
砷
•bronzing
•pyrotechnics
•doping agent in solid-state devices such as
transistors
•the arsenide is used as a laser material to
convert electricity directly into coherent light
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19a–29
Sulfur Isotopes
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19a–30
Frasch
Process for
Extracting
Sulfur
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19a–31
Sulfuric Acid
• concentrated (large amount of solute)
– strong acid
– dehydrating agent
– oxidizing agent
industrial production
• by-product of roasting of sulfide ores or
from scrubbers in fossil fuel burning plants
• produced from elemental sulfur by burning
in air using catalysis (contact process)
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Properties of Sulfuric Acid
• concentrated (large amount of solute)
– strong acid
– dehydrating agent
– oxidizing agent
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Sulfuric Acid Production
S8(s) + 8O2(g) => 8SO2(g)
2 SO2(g) + O2(g) => 2 SO3(g)
SO3(g) + H2O(l) => H2SO4(aq)
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Preparation of Se
Cu2Se + Na2CO3 + 2O2
2CuO + Na2SeO3 + CO2
The selenite Na2SeO3 is acidified with sulphuric
acid. Any tellurites precipitateout leaving
selenous acid, H2SeO3, in solution. Selenium is
liberated from selenous acid by SO2
H2SeO3 + 2SO2 + H2O
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Se + 2H2SO4
19a–35
Downs Cell
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19a–36
Chlor-Alkali Process
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19a–37
Production of Phosphorus
in Electric Furnace
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19a–38
Phosphorus Allotropes
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19a–39
Industrial Preparation by Electrolysis
• Na+ + Cl- + H2O  Na+ + 1/2Cl2 + 1/2H2 + OH-
Laboratory Preparation
MnO2 + 4HCl

MnCl2 + Cl2 + 2H2O
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19a–40
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19a–41
Properties of Bromine
Atomic Number
Density (g/L)
Melting Point (oC)
Boiling Point (oC)
Atomic Radius (pm)
Ionic Radius, Br-1 (pm)
Electronegativity
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35
3.12
-7
59
114
196
2.7
19a–42
Bromine and Iodine
Cl 2 (g) + 2 Br
-
(aq)  Br 2 ( ) + 2 Cl
-
-
Cl 2 (g) + 2 I (aq)  I 2 (aq) + 2 Cl
-
E° = +0.293 V
E° = +0.823 V
Laboratory Preparation:
NaBr (s) + H2SO4 (l)  HBr (g) + NaHSO4 (s)
2HBr (g) + H2SO4 (l)  Br2 (g) + SO2 (g) + 2H2O (l)
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19a–43
Bromine
Use
•fumigants
•flameproofing agents
•water purification
compounds
•dyes
•medicines
• (AgBr) used for
photography
•pesticides
•water purification
•used to make plastics
flame retardant
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19a–44
Properties of Iodine
Atomic Number
Density (g/L)
Melting Point (oC)
Boiling Point (oC)
Atomic Radius (pm)
Ionic Radius, I-1 (pm)
Electronegativity
53
4.92
114
184
133
220
2.2
•iodide, and thyroxin which contains iodine, are used internally in
medicine. A solution of KI and iodine in alcohol is used as a
disinfectant for external wounds.
•silver iodide is used in photography
•nutrient
•added to table salt for nutrition {stops goitres, (Derbyshire neck)}
•deep blue colour in a starch solution is a sign of the free element
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19a–45
Hydrogen Halides HX
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19a–46
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19a–47
bond enthalpy of HX
(kJ mol-1)
electron affinity of X
(kJ mol-1)
hydration enthalpy of X(kJ mol-1)
sum of these
(kJ mol-1)
HF
+562
-328
-506
-272
HCl
+431
-349
-364
-282
HBr
+366
-324
-335
-293
HI
+299
-295
-293
-289
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19a–48