The Representative Elements: Groups 5A Through 8A

1
Chapter 19

• The Representative Elements Groups 5A Through 8A

2
Chapter 19 The Representative Elements
Groups 5A Through 8A
19.1 The Group 5A Elements 19.2 The
Chemistry of Nitrogen 19.3 The Chemistry of
Phosphorous 19.4 The Group 6A Elements 19.5
The Chemistry of Oxygen 19.6 The Chemistry of
Sulfur 19.7 The Group 7A Elements 19.8 The
Group 8A Elements
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
Figure 19.1 Pyramidal shape of the Group 5A
MX3 molecules
8
Figure 19.2 Trigonal bipyramidal shape of the
MX5 molecules
9
Figure 19.3 Octahedral PF6-
10
Figure 19.4 Structures of the tetrahedral MX4
and the octahedral MX6- ions
11
Figure 19.5 Inert atmosphere box
Source Corbis
12
Many Binary Nitrogen compounds decompose
exothermically to give the elements (Pg 893)
N2O(g) N2 (g) ½ O2 (g)
Ho -82 kJ NO(g) ½
N2 (g) ½ O2 (g) Ho -90 kJ NO2
(g) ½ N2 (g) O2 (g)
Ho -34 kJ N2H4 (g) N2
(g) 2 H2 (g) Ho -95
kJ NH3 (g) ½ N2 (g) 3/2 H2
(g) Ho 46 kJ
In This group of compounds only ammonia is
endothermic in its Decomposition.
13
Nitroglycerine C3H5N3O9
H H H
Nitroglycerine is prepared by very
carefully nitrating
glycerine in a mixed H C C C
H nitrating acid bath consisting of
concentrated
nitric and sulfuric acids. O O
O One must be very careful not to
cause
any sharp contact points or any sharp N
N N blows to the
compound, or it will
explode. Any excess heating will
cause O OO OO O immediate
detonation as the reaction is
very exothermic. The
decomposition reaction is 4 C3H5N3O9 (l)
6 N2 (g) 12 CO2 (g) 10 H2O(g) O2
(g) E 4 moles of nitroglycerine produces 29
moles of gaseous products
14
Trinitrotoluene (TNT) C7H5N3O6
CH3
Trinitrotoluene is a relatively stable explosive
made nitrating toluene in the same nitrating
acids as nitroglycerine, but it is much more
stable, will not detonate with out a strong
shock, usually supplied with a blasting cap
containing nitroglycerine.
NO2
NO2
NO2
The decomposition reaction for Trinitrotoluene
is 2 C7H5N3O6 (s) 12 CO(g) 5 H2
(g) 3 N2 (g) 2 C(s) E 2 moles of TNT
produce 20 moles of gaseous products
15
Figure 19.6 Schematic diagram of the Haber
process for the manufacture of ammonia.
16
Figure 19.7 Nitrogen cycle
17
Nodules on the roots of pea plants contain
nitrogen-fixing bacteria.
Source Photo Researchers, Inc.
18
Figure 19.8 Molecular structure of hydrazine
(N2H4)
19
(No Transcript)
20
Blowing agents--such as hydrazine, which forms
nitrogen gas on decomposition--are used to
produce porous plastics like these polystyrene
products.
21
(No Transcript)
22
(No Transcript)
23
Copper penny reacts with nitric acid to produce
NO gas, which is immediately oxidized in air to
give reddish brown NO2-.
Source Fundamental Photographs
24
Figure 19.9 Molecular orbital energy-level
diagram for nitric oxide (NO).
25
(No Transcript)
26
(No Transcript)
27
Kissing bug
Source Photo Researchers, Inc.
28
Three-dimensional complex nitrohphorin-1
Source Department of Biochemistry, University of
Arizona, Tuscon
29
Figure 19.10 Ostwald process
30
Figure 19.11 (a) molecular structure of HNO3
(b) resonance structure
31
(No Transcript)
32
White phosphorous reacts vigorously with the
oxygen in air and must be stored under water.
Red phosphorus is stable in air.
Source Stock Boston
33
Figure 19.12 (a) P4 molecule found in white
phosphorous (b) crystalline network structure of
black Phosphorous (c) chain structure ofred
phosphorous
White Black
Red Phosphorous
34
(No Transcript)
35
(No Transcript)
36
Figure 19.13 Structures of P4O6 and P4O10
37
(No Transcript)
38
(No Transcript)
39
Lewis structure and Molecular model of Phosphoric
acid (H3PO4)
HOPOH O H
..
..
O
..
..
..
..
..
..
40
Figure 19.14 Structures of (a) phosphorus acid
(H3PO3), and (b) hypophosphorous acid (H3PO2)
41
Phosphorous in Fertilizers
Phosphorous is one of the essential elements for
life, and is required in Fertilizers for plants
to grow. Super phosphate of lime
CaSO4 2 H2O
and Ca(H2PO4)2 H2O Triple phosphate
Ca(H2PO4)2 Reaction of
Ammonia and Phosphoric acid gives
ammonium dihydrogen phosphate (NH4)H2PO4
This compound not only has phosphorous, but
Nitrogen as well.
42
Phosphorous Halides
The general formulas are PX3 and PX5 PF3
is a gas PCl3 is a liquid ( bp 74oC)
PBr3 is a liquid (bp 175oC) PI3 is an
unstable red solid (mp 61oC) PX3 3 H2O(l)
H3PO3 (aq) 3 HX(aq) PCl5 is an
ionic solid of PCl6- and PCl4 ions. PBr5 is
an ionic solid of PBr4 and Br - ions. The
PX5 compounds react with water to form
Phosphoric acid. PX5 4 H2O(l)
H3PO4 (aq) 5 HX(aq)
43
Figure 19.15 Structures of the phosphorous
halides (a) PX3 compounds have pyramidal
molecules (b) the gaseous and liquid phases of
PX5 compound are trigonal bipyramidal molecules
44
Important Reactions of the Nitrogen Family - I
1.Nitrogen is fixed industrially in the Haber
process Further reactions convert NH3 to
NO, NO2, and HNO3. Some other group hydrides
are formed from reaction in water (or H3O) of
metal phosphide, arsenide, and so forth 2.
Halides are formed by direct combination of the
elements 3.Oxoacids are formed from the
halide with a reaction in water that is common
to many nonmetal halides
N2 (g) 3 H2 (g)
_______________
Ca3P2 (s) 6 H2O(l)
____________________________
2 M(s) 3X2 (-) 2 MX3 (-) (M
all except N) MX3 (-) X2 (-)
MX5 (-) (M all except N and Bi)
MX3 (-) 3 H2O(l)
______________________ ( M
all except N)
45
Important Reactions of the Nitrogen Family - II
3. continued Note that the oxidation
number of element does not change. 4. Phosphate
ions are dehydrated to form polyphosphates 5.
When P4 reacts in basic solution, its oxidation
state both decreases and increases Analog
ous reactions are typical of many nonmetals, such
as S8 and X2.
MX5 (-) 4 H2O(l)
____________________________
M all except N and Bi)
3 NaH2PO4 (s)
___________________________
P4 (s) 3 OH-(aq) 3 H2O(l)
PH3 (g) 3 H2PO2-(aq)
46
Important Compounds in the Nitrogen Family - I
1. Ammonia, NH3. First substance formed when
atmospheric N2 is used to make N - containing
compounds. Annual multimillion - ton
production for use in fertilizers, explosives,
rayon, and polymers such as nylon,
urea-formaldehyde resins, and acrylics. 2.
Hydrazine, N2H4. Nitrogens other hydride. Used
in rockets as a propellant, and as a
starting point for antituberculin drugs. 3.
Nitric oxide (NO), nitrogen dioxide (NO2), and
nitric acid (HNO3). Oxides are intermediates
to HNO3. Acid used in fertilizer
manufacture, nylon production, metal etching, and
explosives industry. 4. Amino acids,
H3N-CH(R)-COO- (R one of 20 different organic
groups). Occur in every organism, both free
and linked together into proteins. Essential
to growth and function of all cells. Synthetic
amino acids used as dietary supplements.
47
Important Compounds in the Nitrogen Family-II
5. Phosphorous trichloride, PCl3. Used to form
many organic phosphorous compounds,
including oil and fuel additives, plasticizers,
flame retardants, and insecticides. Also used
to make PCl5, POCl3, and other important
P-containing compounds. 6. Tetraphosphorous
decoxide (P4O10) and phosphoric acid (H3PO4)
Many uses, and probably the most important P
chemicals. 7. Sodium triphosphate, Na5P3O10. As a
water-softening agent (Calgon), combines with
hard-water Mg2and Ca2 ions, preventing them
from reacting with soap anions, and thus
improves cleaning action. Use curtailed in
the United States because it pollutes lakes and
streams by causing excessive algae
growth. 8. Adenosine triphosphate (ATP) and other
biophosphates. ATP acts to transfer chemical
energy in the cell necessary for all biological
processes requiring energy. Phosphate groups
occur in sugars, fats, proteins, and nucleic
acids. 9. Bismuth subsalicylate, BiO(C7H5O3). The
material in Pepto-Bismol.
48
The Stepwise Ionization Neutralization of
Phosphoric Acid
H3PO4 (aq) H2O(l)
H2PO4- (aq) H3O(aq) H2PO4-(aq) H2O(l)
HPO4-2(aq)
H3O(aq) HPO4-2(aq) H2O(l)
PO4-3(aq) H3O(aq) H3PO4 (aq) 3
H2O(l) PO4-3(aq) 3
H3O(aq)
H3PO4 (aq) NaOH(aq)
NaH2PO4 (aq) H2O(l) NaH2PO4 (aq) NaOH(aq)
Na2HPO4 (aq)
H2O(l) Na2HPO4 (aq) NaOH(aq)
Na3PO4 (aq) H2O(l) H3PO4 (aq) 3
NaOH(aq) Na3PO4 (aq)
3 H2O(l)
49
(No Transcript)
50
(No Transcript)
51
(No Transcript)
52
Walnuts contain trace amounts of selenium.
Source Alamy Images
53
(No Transcript)
54
U.S. Navy test pilot in an F-14 jet using an
oxygen mask.
Source Photo Researchers, Inc.
55
(No Transcript)
56
Sources of Sulfur on Earth
Elemental Sulfur is found on the Earth in
Volcanic deposits Fumaroles Underground
deposits Common Minerals containing Sulfur
PbS Galena HgS Cinnabar FeS2
Pyrite CaSO4 2 H2O Gypsum
MgSO4 7 H2O Epsomite Na2SO4 CaSO4 -
Galberite
57
Figure 19.16 Frasch method for recovering
sulfur from underground deposits.
58
Melted sulfur obtained from underground deposits
by the Frasch process.
Source Photo Researchers, Inc.
59
Figure 19.17 (a) the S8 molecule (b) chains of
sulfur atoms in viscous liquid sulfur. The chains
may contain as many as 10,000 sulfur atoms.
60
(No Transcript)
61
Crystals of rhombic sulfur
Crystals of monoclinic sulfur
Source Color-Pic, Inc.
62
Pouring liquid sulfur into water to produce
plastic sulfur.
Source American Color
63
(No Transcript)
64
Figure 19.19 (a) Two resonance structures for
SO2 (b) The SO2 molecule is a bent molecule as
predicted by the VSEPR model
65
Figure 19.20 (a) The resonance structures most
commonly given for SO3 (b) a resonance structure
with three double bonds (c) SO3 is a planar
molecule with three equal bonds
66
Figure 19.21 Different structures for solid SO3
S3O9 rings
In both cases the sulfur atoms are surrounded by
a tetrahedral arrangement of oxygen atoms.
(SO3)x chains
67
Oxyacids of sulfur
There are two important Oxyacids of sulfur, they
are formed by The reaction of the oxides of
sulfur with water. SO2 (g) H2O(g)
H2SO3 (aq) Sulfurous acid
H2SO3 (aq) H2O(l) H3O(aq)
HSO3-(aq) Ka1 1.5 x 10-2 HSO3-(aq)
H2O(l) H3O(aq) SO3-2(aq)
Ka2 1.0 x 10-7 SO3 (g) H2O(l)
H2SO4 (aq) Sulfuric acid
H2SO4 (aq) H2O(l) H3O(aq)
HSO4-(aq) Ka1 Large HSO4-(aq)
H2O(l) H3O(aq) SO4-2(aq)
Ka2 1.2 x 10-2
68
Figure 19.22 Reaction of H2SO4 with sucrose to
produce a blackened column of carbon.
69
(No Transcript)
70
(No Transcript)
71
Figure 19.23 Structures of (a) SF4 (b) SF6 (c)
S2F10 (d) S2CL2
SF4
S2F10
S2Cl2
SF6
72
Important Reactions of the Oxygen Family - I
1. Halides are formed by direct
combination 2. The other elements in the
group are oxidized by O2 SO2 is oxidized
further, and the product is used in the final
step of H2SO4 manufacture.
M(s) X2 (g) various
halides (M S, Se, Te X F, Cl)
M(s) O2 (g) MO2 (-)
(M S, Se, Te, Po)
2 SO2 (g) O2 (g)
_________ SO3 (g) H2O(l)
___________
73
Important Reactions of the Oxygen Family - II
3. Sulfur is recovered when hydrogen sulfide is
oxidized This reaction is used to obtain
sulfur when natural deposits are not
available. 4. The thiosulfate ion is formed when
an alkali sulfite reacts with sulfur, as in
the preparation of photographers hypo
8 H2S(g) 4 O2 (g)
_____________________
S8 (s) 8 Na2SO3 (aq)
______________________
74
Important Compounds of the Oxygen Family - I
1. Water, H2O. The single most important compound
on earth! 2. Hydrogen peroxide, H2O2. Used as an
oxidizing agent, disinfectant, bleach, and
in the production of peroxy compounds for
polymerization. 3. Hydrogen sulfide, H2S.
Vile-smelling toxic gas formed during
anaerobic decomposition of plant and animal
matter, in volcanoes, and in deep sea thermal
vents. Used as a source and in the manufacture of
paper. Atmospheric traces cause silver to
tarnish through formation of black Ag2S. 4.
Sulfur dioxide, SO2. Colorless, choking gas
formed in volcanoes or whenever an
S-containing compound (coal, oil, metal sulfide
ores, and so on) is burned. More than 90 of
SO2 produced is used to make sulfuric acid.
Also used as a fumigant and preservative of
fruit, syrups, and wine. As a reducing agent,
removes excess Cl2 from industrial waste
water, removes O2 from petroleum handling tanks,
and prepares ClO2 for bleaching paper. Major
atmospheric pollutant in acid rain.
75
Important Compounds of the Oxygen Family - II
5. Sulfur trioxide (SO3) and sulfuric acid
(H2SO4). SO3 , formed from SO2 over V2O5
catalysts, is then converted to sulfuric acid.
The acid is the cheapest strong acid and is
so widely used in industry that its
production level is an indicator of a nations
economic strength. Strong dehydrating agent
that removes water from any organic source. 6.
Sulfur hexafluoride, SF6. Extremely inert gas
used as an electrical insulator. Also used
as an atmospheric tracer of air movement over
extremely great distances.
O - S - Se - Te - Po
76
(No Transcript)
77
(No Transcript)
78
(No Transcript)
79
(No Transcript)
80
(No Transcript)
81
Gaseous Liquid Solid Chlorine
Bromine Iodine
82
(No Transcript)
83
(No Transcript)
84
Candle burning in an atmosphere of Cl2(g).
Source Phototake
85
(No Transcript)
86
Figure 19.24 Hydrogen bonding among HF
molecules in liquid hydrogen fluoride.
87
(No Transcript)
88
(No Transcript)
89
Figure 19.25 Structures of the oxychloro
anions.
90
(No Transcript)
91
(No Transcript)
92
(No Transcript)
93
Figure 19.26 Idealized structures of the
interhalogens CIF3 and IF5.
94
(No Transcript)
95
Halogen Oxides, Oxoacids and Oxoanions
Production of chlorine dioxide
2 NaClO3 (s) SO2 (g) H2SO4 (aq)
_____________________
Preparation of dichlorine heptaoxide by the
condensation of perchloric acid
O3Cl OH HO ClO3
H2O(l) O3Cl O ClO3 (l)
Decomposition of chlorates to give oxygen
2 KClO3 (s)
_______________________
Ammonium perchlorate and Al used in the space
shuttle boosters
10 Al(s) 6 NH4ClO4 (s) 4 Al2O3 (s)
12 H2O(g) 3 N2 (g) 2 AlCl3 (g)
96
Important Reactions of the Halogens - I
1. The halogens (X2) oxidize many metals and
non-metals. The reaction with hydrogen,
although not used commercially for HX production
(except for high-purity HCl), is
characteristic of these strong oxidizing
agents. 2. The halogens disproportionate in
water In aqueous base, the reaction goes
to completion to form hypohalites and, at
higher temperatures, halates for example
X2 (-) H2 (g)
______________
X2 (-) H2O(l)
___________________ X
Cl, Br, I
3 Cl2 (g) 6 OH-(aq)
_________________________
97
Important Reactions of the Halogens - II
3. Molecular Fluorine, F2 is produced
electrolytically at moderate temperature
A major use of F2 is in the preparation of UF6
for nuclear fuel. 4. Glass (amorphous silica) is
etched with HF
2HF (as KHF2, a solution of KF in HF)
H2 (g) F2 (g)
SiO2 (s) 6 HF(g)
______________________
F - Cl - Br - I - At
98
Important Compounds of the Halogens - I
1. Fluorspar (fluorite), CaF2. Widely distributed
mineral used as a flux in steel making and
in the production of HF. 2. Hydrogen fluoride,
HF. Colorless, extremely toxic gas used to make
F2, organic fluorine compounds, and polymers.
Also used in aluminum manufacture and in
glass etching. 3. Hydrogen chloride, HCl.
Extremely water-soluble gas that forms
hydrochloric acid, which occurs naturally in
stomach juice of mammals (humans produce
1.5L of 0.1 M HCl daily) and in volcanic
gases (from reaction of H2O on sea salt). Made by
reaction of NaCl and H2SO4 and as a
by-product of plastics (PVC) production. Used in
the pickling of steel (removal of adhering
oxides) and in the production of syrups,
rayon, and plastic.
99
Important Compounds of the Halogens - II
4. Sodium hypochlorite, NaClO, and calcium
hypochlorite, Ca(ClO)2. Oxidizing agents used
to bleach wood pulp and textile, and disinfect
swimming pools, foods, and sewage (also used to
disinfect the Apollo 11 on return from the
moon). Household bleach is 5.25 NaClO by
mass in water. 5. Ammonium perchlorate, NH4ClO4.
Strong oxidizing agent used in the space
shuttle program. 6. Potassium iodide, KI. Most
common soluble iodide. Table salt additive
to prevent thyroid disease (goiter). Used in
chemical analysis because it is easily
oxidized to I2, which forms a colored end
point. 7. Polychorinated biphenyls, PCBs. Mixture
of chlorinated organic compounds used as
nonflammable insulating liquids in electrical
transformers. Production discontinued due to
persistence in the environment, where it
becomes concentrated in fish, birds, and
mammals, and causes reproductive disturbances and
possibly cancer.
100
(No Transcript)
101
(No Transcript)
102
(No Transcript)
103
(No Transcript)
104
Figure 19.27 Structures of several known xenon
compounds
105
Neon sign maker and artist Jess Baird shows off a
few of the items he has made in his Weatherford,
Texas, shop.
Source AP/Wide World Photos
106
Crystals of Xenon tetrafluoride (XeF4)
107
The Periodic Table of the Elements
H
He
Elements that are polyatomic in their
natural state
Li
Be
B
C
N
O
F
Ne
Na
Mg
Ar
Al
Si
P
S
Cl
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
Sb
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
Xe
I
Te
Sn
In
Cs
Ba
La
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Rn
At
Po
Bi
Pb
Tl
Fr
Ra
Ac
Rf
Du
Sg
Bo
Ha
Me
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
Th
Pa
U
Np
Pu
Am
Cm
Bk Cf
Es
Fm
Md
No
Lr
Diatomic
Octatomic ( 8 atoms per molecule)
Tetratomic ( 4 atoms per molecule)