???? ???? Chapter 12 Oxygen Family Elements

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???? ???? Chapter 12 Oxygen Family Elements

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Title: ???? ???? Chapter 12 Oxygen Family Elements

1
???? ???? Chapter 12 Oxygen Family
Elements
2

Oxygen Sulphur Selenium
O S Se
Tellurium Polonium
Te Po
???????
(ore-forming element)

12-1 Oxygen and its compounds
??Simple substance
1. ??He?Ne?Ar??,???????
?,???????,??????
2. ????????-2,??2 (OF2) ,
4O(O2) , 1(O2F2) , -1(H2O2)
3. ????????142KJmol-1,??
?268KJmol-1????????494 kJ/mol

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??
(1) ???????,??????????
?????
(2) ???????d??,????dp??,??OO????
??O2????,??s??,?????
??p?,??O22O????,?????
2000oC ,???????
????????????,?58(?mol?)

??Compounds
1. -2O.S.
??????????
???????????,
?????????????
??
???????
(sS) 2(sZ) 2(sXnon) 2(pYnon)2

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8
The 1s, 2s and 2pz orbitals of oxygen are
symmetric (i.e., unchanged) with respect to all
three symmetry operations. They are given the
symmetry classification a1. The 2px orbital,
since it possesses a node in the s2 plane (and
hence is of different sign on each side of the
plane) changes sign when reflected through the s2
plane or when rotated by 180 about the C2 axis.
It is classified as a b2 orbital. The 2py orbital
is antisymmetric with respect to the rotation
operator and to a reflection through the s1
plane. It is labelled b1.    The hydrogen 1s
orbitals when considered separately are neither
unchanged nor changed in sign by the rotation
operator or by a reflection through the s2 plane.
Instead both these operations interchange these
orbitals. The hydrogen orbitals are said to be
symmetrically equivalent and when considered
individually they do not reflect the symmetry
properties of the molecule. However, the two
linear combinations (1s1 1s2) and (1s1 -
1s2) do behave in the required manner. The former
is symmetric under all three operations and is
of a1 symmetry while the latter is antisymmetric
with respect to the rotation operator and to a
reflection through the plane s2 and is of b2
symmetry.    The molecular orbitals in the water
molecule are classified as a1, b1 or b2 orbitals,
as determined by their symmetry properties. This
labelling of the orbitals is analogous to the use
of the s-p and g-u classification in linear
molecules. In addition to the symmetry properties
of the atomic orbitals we must consider their
relative energies to determine which orbitals
will overlap significantly and form delocalized
molecular orbitals.
9
The molecular orbitals in the water molecule are
classified as a1, b1 or b2 orbitals, as
determined by their symmetry properties. This
labelling of the orbitals is analogous to the use
of the s-p and g-u classification in linear
molecules. In addition to the symmetry properties
of the atomic orbitals we must consider their
relative energies to determine which orbitals
will overlap significantly and form delocalized
molecular orbitals.    The 1s atomic orbital on
oxygen possesses a much lower energy than any of
the other orbitals of a1 symmetry and should not
interact significantly with them. The molecular
orbital of lowest energy in H2O should therefore
correspond to an inner shell 1s atomic-like
orbital centred on the oxygen. This is the first
orbital of a1 symmetry and it is labelled la1.
Reference to the forms of the charge density
contours for the la, molecular orbital
substantiates the above remarks regarding the
properties of this orbital. Notice that the
orbital energy of the la1 molecular orbital is
very similar to that for the 1s atomic orbital on
oxygen. The 1a1 orbital in H2O is, therefore,
similar to the ls inner shell molecular orbitals
of the diatomic hydrides.    The atomic orbital
of next lowest energy in this system is the 2s
orbital of a1 symmetry on oxygen. We might
anticipate that the extent to which this orbital
will overlap with the (1s1 1s2) combination of
orbitals on the hydrogen atoms to form the 2a1
molecular orbital will be intermediate between
that found for the 2s molecular orbitals in the
diatomic hydrides CH and HF. The 2s orbital in CH
results from a strong mixing of the 2s orbital on
carbon and the hydrogen 1s orbital. In HF the
participation of the hydrogen orbital in the 2s
orbital is greatly reduced, a result of the lower
energy of the 2s atomic orbital on fluorine as
compared to that of the 2s orbital on carbon.
10
   Aside from the presence of the second proton,
the general form and nodal structure of the 2a1
density distribution in the water molecule is
remarkably similar to the 2s distributions in CH
and HF, and particularly to the latter. The
charge density accumulated on the bonded side of
the oxygen nucleus in the 2a1 orbital is
localized near this nucleus as the corresponding
charge increase in the 2s orbital of HF is
localized near the fluorine. The charge density
of the 2a1 molecular orbital accumulated in the
region between the three nuclei will exert a
force drawing all three nuclei together. The 2a1
orbital is a binding orbital.    Although the
three 2p atomic orbitals are degenerate in the
oxygen atom the presence of the two protons
results in each 2p orbital experiencing a
different potential field in the water molecule.
The nonequivalence of the 2p orbitals in the
water molecule is evidenced by all three
possessing different symmetry properties. The
three 2p orbitals will interact to different
extents with the protons and their energies will
differ.    The 2px orbital interacts most
strongly with the protons and forms an orbital of
b2 symmetry by overlapping with the (1s1 - 1s2)
combination of 1s orbitals on the hydrogens. The
charge density contours for the lb2 orbital
indicate that this simple LCAO description
accounts for the principal features of this
molecular orbital. The lb2 orbital concentrates
charge density along each O-H bond axis and draws
the nuclei together. The charge density of the
1b2 orbital binds all three nuclei. In terms of
the forces exerted on the nuclei the 2a1 and lb2
molecular orbitals are about equally effective in
binding the protons in the water molecule.
11
The 2pz orbital may also overlap with the
hydrogen 1s orbitals, the (1s1 1s2) a1
combination, and the result is the 3a1 molecular
orbital. This orbital is concentrated along the
z-axis and charge density is accumulated in both
the bonded and nonbonded sides of the oxygen
nucleus. It exerts a binding force on the protons
and an antibinding force on the oxygen nucleus, a
behaviour similar to that noted before for the 3s
orbitals in CH and HF.     The 2py orbital is
not of the correct symmetry to overlap with the
hydrogen 1s orbitals. To a first approximation
the 1b1 molecular orbital will be simply a 2py
atomic orbital on the oxygen, perpendicular to
the plane of the molecule. Therefore, the 1b1
orbital does resemble a 2p atomic orbital on
oxygen but one which is polarized into the
molecule by the field of the protons. The 1b1
molecular orbital of H2O thus resembles a single
component of the 1p molecular orbitals of the
diatomic hydrides. The 1b1 and the 1p orbitals
are essentially nonbinding. They exert a small
binding force on the heavy nuclei because of the
slight polarization. The force exerted on the
protons by the pair of electrons in the 1b1
orbital is slightly less than that required to
balance the force of repulsion exerted by two of
the nuclear charges on the oxygen nucleus. The
1b1 and 1p electrons basically do no more than
partially screen nuclear charge on the heavy
nuclei from the protons.
12
In summary, the electronic configuration of the
water molecule as determined by molecular orbital
theory is 1a212a211b223a211b21 The la1 orbital
is a nonbinding inner shell orbital. The pair of
electrons in the la1 orbital simply screen two of
the nuclear charges on the oxygen from the
protons. The 2a1, 1b2 and 3a1 orbitals accumulate
charge density in the region between the nuclei
and the charge densities in these orbitals are
responsible for binding the protons in the water
molecule. Aside from being polarized by the
presence of the protons, the lb1 orbital is a
non-interacting 2py orbital on the oxygen and is
essentially nonbinding.
http//www.chemistry.mcmaster.ca/esam/Chapter_8/se
ction_6.html
13
Contents from http//butane.chem.uiuc.edu/pshapley
/312/Lectures/L10/index.html
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B2 A1
16
2px B1 2py B2
17
2px B1 2py B2
18
2px B1 2py B2
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Contour maps of the molecular orbital charge
densities for H2O. The maps for the la1, 2a1,
3a1and 1b2 orbitals (all doubly-occupied) are
shown in the plane of the nuclei. The lb1 orbital
has a node in this plane and hence the contour
map for the 1b1 orbital is shown in the plane
perpendicular to the molecular plane. The total
molecular charge density for H2O is also
illustrated. The density distributions were
calculated from the wave function determined by
R. M. Pitzer, S. Aung and S. I. Chan, J. Chem.
Phys. 49, 2071 (1968).
http//www.chemistry.mcmaster.ca/esam/Chapter_8/se
ction_6.htmlFig_8-11.
21

2. -1 O.S.
The most important peroxide is that of
hydrogen
(1) Structure
?????,????????????
(2) Properties
????????????,????,???
??????hydrogen bond , ???????
330?????????????(perhydrol)

b. H2O2?????
H2O2 H2O H3O HO2-
c. ??????,H2O2???????,
??????,H2O2????????
?????????,??????,??
???,??????????????
2H H2O2 2e 2H2O
O2 2H 2e H2O2

d. ?????????H2O2???
(i) ?OH-????H??????
(ii) ???????Fe2 , Mn2 , Cu2 ,
Cr2??????H2O2???
(iii) ???320380nm????H2O2
??
(iv) ??????

24
Bubble-Propelled Micromotors
http//pubs.acs.org/doi/full/10.1021/ja411705d
25

(3) Preparation
a. BaO2 H2SO4 BaSO4? H2O2
BaO2 CO2 H2O BaCO3 H2O2
b. ?????
??2NH4HSO4 (NH4)2S2O8 H2?
?????????
(NH4)2S2O8 2H2SO4 H2S2O8 2NH4HSO4
H2S2O8 H2O H2SO4 H2SO5
H2SO5 H2O H2SO4 H2O2

C. ?????
H2 O2 H2O2 (????????)
(4) Application
??H2O2????,????????
??????
?????????
??H2O2????,???Cl2
3?H2O2?????

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(5) Identification
???????????,????????????????,????????
CrO(O2)2(C2H5)2O
????????,??????CrO42-?Cr2O72-
?????,?????CrO5??H2O2??,??O2?

3. I , II , IV O.S.
O2F2 , OF2 , O(O2)
(1) O2F2 dioxydifluoride
?????,?H2O2????,????
???
O2 F2 O2F2 ???
O2F2 PtF5 O2PtF6- 1/2F2
????O2F2??????????

(2) OF2 Oxygen difluoride
??????,??,?????,???
??????
2F2 2NaOH OF2 2NaF H2O
(3) O3 Ozone
???O(O2),????O2??????
(allotrope)

a. ???????(diamagnetic material)
????s?,??34? ????????
?SP2??,???????????????
?????s?,??????????????,??snon ?
b. Physical properties
????????????,??????
???O3?????????O3??????

??O3????,??O3????,??
O3????????????O2 ,????
???O2?,?O2????,????
c. Chemical properties
?G
-326KJmol-1
???????O2 ,?
O3 XeO3 2H2O H4XeO6 O2?
PbS 4O3 PbSO4 4O2?
2I- O3 H2O I2 O2 2OH- ??????I-

d. Preparation
3O2 2O3 ??????hv,??????25
km??????
e. Applications
?????CN-???,???????????
?????,????????
?????,??????????????
CH3CH2CHCH2 CH3 CH2CHO HCHO
CH3CHCHCH3 2CH3CHO

12-2 Sulfur and its compounds
??The simple substance
1. ?????????????,????
??,????
2H2S SO2 3S? 2H2O
2H2S O2 2S? 2H2O
?????H2S????????????
??????

2. Allotrope
(1) S8??????,???(ring)?
???(crown)
??????
??(??)?(orthorhombic)???
???(monoclinic)?????
(2) Allotrope???
S2?????,?S4 , S6 , S8 ??????

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3. Chemical properties
(1) ????(??????N2?I2)???(?Au?Pt)???
2Al 3S Al2S3 Fe S FeS
Hg S HgS (??) S O2 SO2
(2) ???????????
3S 6NaOH 2Na2S Na2SO3 3H2O
4. preparation
3FeS2 12C 8O2 Fe3O4 12CO 6S

??Compounds 1. -2 O.S.
(1) Hydrolysis
S2- H2O HS- OH-
SiS2 3H2O H2SiO3 2H2S
Al2S3 6H2O 2Al(OH)3 3H2S
(2) interaction
Na2S CS2 Na2CS3
Na2CS3 H2SO4 Na2SO4 H2CS3
H2CS3 H2S CS2

(3) reduction
??????S?SO2?H2SO4,????
???
2KMnO4 5H2S 3H2SO4
2MnSO4 5S? K2SO4 8H2O
2H2S O2 2S? 2H2O
H2S I2 2HI S?
H2S 4Br2 4H2O H2SO4 8HBr

(4) ?????????????,???
??,?????
????????,????,????????????????
(5)????????????????
e.g. TiS2 Metallic conductivity,
ZrS2 Semiconductivity,
HfS2 Dielectric

As2S3 yellow ZnS White Ga2S3 Yellow GeS2 White
Sb2S3 orange CdS Yellow In2S3 Yellow SnS2 Yellow
Bi2S3 black HgS black Tl2S3 black PbS black
41

2. -2/n O.S. ????
( polysulfide or persulfide )
(1) Na2S (n-1)S Na2Sn ??
H2Sn
(NH4)2S (N-1)S (NH4)2Sn ???
(2) Redox reactions
3Na2S2 As2S3 2Na3AsS4 S
4FeS2 11O2 2Fe2O3 8SO2

H2S (n-1)S
42

3. 4 O.S.
SHal4(SF4) SOHal2(SOF2?SOCl2) SO2
(1) ?H2O??
SO2 H2O H2SO3
???????????,???????
SOCl2 2H2O 2HCl H2SO3
SF4 3H2O 4HF H2SO3
(2) ?????,?????,???????
SO2 H2S 3S 2H2O
SO2 Br2 2H2O H2SO4 2HBr
4Na2SO3 3Na2SO4 Na2S (??)

4. 6 O.S.
(1) ?????????,???,???,?????
(2) SF6 SF6 3H2O SO3 6HF
????????Gltlt0,?SF6????,????
?,???????????????
SF6??????,??????????(6)??
??(6)???????????,?????????
(19.3 ev), SF6????,?????,?????
????????????

(3) S(VI)????????????4,??SO3?????(polymerize),??
??
SO3 HF HSO3F
??HSO3F????HClO4
???,?SbF5 HSO3F?
????

45
Superacid and Superbase
Olah received the 1994 Nobel Prize in Chemistry
for his pioneering research on carbocations and
their role in the chemistry of hydrocarbons. In
particular, he developed superacids (a term he
coined) that are much stronger than ordinary
acids, are non-nucleophilic, and are fluid at low
temperatures. In such media (examples include
HF-SbF5 and SbF5-SO2ClF-SO2F2) carbocations are
stable and their physical properties, such as NMR
spectra, can be observed, thus allowing details
of their structures to be determined. Besides
trivalent ions, of which CH3 is the parent, Olah
demonstrated the existence of higher coordinate
carbocations such as CH5. These species do not
violate the octet rule, but involve 2-electron
3-center bonding. Olah was born and educated in
Hungary, moved to Canada (Dow Chemical) after the
1956 Hungarian uprising, and ultimately to the
U.S.A. He was professor and chairman of chemistry
at Case Western Reserve University before moving
to the University of Southern California, where
he is distinguished professor at USC's Loker
Hydrocarbon Research Institute. Olah's many
honors besides the Nobel include the ACS awards
in Petroleum Chemistry(1964) and for Creative
Work in Synthetic Organic Chemistry (1979), and
the Roger Adams Award in Organic Chemistry (1989).
George Andrew Olah HungarianAmerican chemist
(1927) Olah's "magic acid", so-named for its
ability to attack hydrocarbons, is prepared by
mixing antimony pentafluoride (SbF5) and
fluorosulfuric acid. The name was coined after
one of Professor Olah's post-doctoral associates
placed a candle in a sample of magic acid. The
candle was dissolved, showing the ability of the
acid to protonate hydrocarbons (which are not
basic).
46
Superacid and Superbase

A superacid is an acid with an acidity greater
than that of 100 sulfuric acid, which has a
Hammett acidity function of -12. Commercially
available superacids include trifluoromethanesulfo
nic acid (CF3SO3H), also known as triflic acid,
and fluorosulfuric acid (FSO3H), both of which
are about a thousand times stronger (i.e. have
more negative H0 values) than sulfuric acid. The
strongest superacids are prepared by the
combination of two components, a strong Lewis
acid and a strong Brønsted acid.
The strongest super acid system, the so-called
fluoroantimonic acid, is a combination of
hydrogen fluoride and SbF5. In this system, HF
releases its proton (H) concomitant with the
binding of F- by the antimony pentafluoride. The
resulting anion (SbF6-) is both a weak
nucleophile and a weak base. The proton
effectively becomes "naked", which accounts for
the system's extreme acidity. Fluoroantimonic
acid is 21019 times stronger than 100 sulfuric
acid, and can produce solutions with a pH down to
25.

47
Superacid and Superbase

In chemistry, a superbase is an extremely strong
base. There is no commonly accepted definition
for what qualifies as a superbase, but most
chemists would accept sodium hydroxide as a
'benchmark' base just as sulfuric acid is a
'benchmark' acid (see superacid). The hydroxide
ion is a good benchmark because it is the
strongest base that can exist in a water
solution stronger bases neutralize water as an
acid by deprotonation, to produce hydroxide (and
protonated superbase). Another use that can
define superbase is stoichiometric
a-deprotonation of a carbonyl compound into an
enolate, something that cannot be done by
"regular bases". Despite this, the term still
doesn't have a standard chemical definition, so
for example Proton Sponge may be called
"superbase".
Organometallic compounds of reactive metals are
usually superbases, for example organolithium and
organomagnesiums (Grignard reagents). Another
type of organic superbase has a reactive metal
exchanged for a hydrogen on a heteroatom, such as
oxygen (unstabilized alkoxides) or nitrogen
(lithium diisopropylamide).

48
Superacid and Superbase

Reactions involving superbases are usually
water-sensitive, conducted under an inert
atmosphere and at a low temperature. A desirable
property in many cases is low nucleophilic
reactivity, i.e. a non-nucleophilic base.
Unhindered alkyllithiums, for example, cannot be
used with electrophiles such as carbonyl groups,
because they attack the electrophiles as
nucleophiles.
In organic synthesis, the Schlosser base (or
Lochmann-Schlosser base), i.e. the combination of
n-butyllithium and potassium tert-butoxide, is a
commonly used superbase. Butyllithium exists as
four-, or six-membered clusters, which are
kinetically slow to react. The tertiary
alcoholate (butoxide) serves to complex the
lithium ion, which breaks the butyllithium
clusters. This makes the butyllithium kinetically
more reactive.
Inorganic superbases are typically salts with
highly charged, small negative ions, e.g. lithium
nitride, which has extreme negative charge
density and so is highly attracted to acids, like
the aqueous hydronium ion. Alkali and earth
alkali metal hydrides (sodium hydride, calcium
hydride) are superbases.