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Unformatted text preview: Ch102
Sample
PresentaGon
by
Wilson
Ho
 Allotropes
of
Phosphorus
 •  •  •  Phosphorus
has
at
least
12
allotropes.
 Most
common
are
white
and
red
phosphorus.
Black
phosphorus
is
most
stable.
 White
phosphorus
(P4)
ignites
spontaneously
in
air.
Used
in
military
weapons
and
smoke
 devices.
Highly
toxic,
reacGve
with

halogens
and
metals.
 1700 K +2 +0 +5 +0 Synthesis:

 OxidaGon
State
 P4 + 6 CaSiO3 + 10 CO 2 Ca3(PO4)2 + 6 SiO2 + 10 C 
 
 
Oxidant:
P
in
Ca3(PO4)2












Reductant:
C
 •  Red
phosphorus
structure
consists
of
chains,
perpendicularly
cross‐linked
at
the
P ‐P 
 juncGon
(the
P 
is
in
a
different
chain).

Not
toxic,
less
reacGve
than
white
form
toward
 540 K halogens
and
metals,
and
also
less
flammable.
Synthesis:
 White P i nert at mospher e •  Black
phosphorus
is
similar
to
graphite
in
structure
and
physical
properGes
(black,
smooth,
 and
electrically
conducGve).
Not
toxic,
nonflammable,
chemically
inert
up
to
high
 temperatures.
Synthesis:

 ! White P 12,000 at m +0 •  ! P4 + 3 NaOH + 3 H2O DisproporGonaGon
of
P4:
 
 
 
 Black P +1 -3 3 NaH2PO2 + PH3 
Oxidant
and
Reductant:
P4
 P' ' P P' P P P P P P P P P P P P P P P P P P P P P P P P P White Red Reference:
HousecroU
and
Sharpe,
Inorganic
Chemistry,
3rd
ed.,
2008.

 P P P P P P P P Black P P P Red P White
Phosphorus
 •  P4
has
Td
symmetry:
 S4
axis
straight
 down
into
paper.
 
 σd
plane
perp.
to
 paper,
through
 bolded
bond.
 HOMO,
mix
of
 bonding
and
 anGbonding.
 NoGce
increased
 electron
density
 between
some
P
 atoms
and
 decreased
density
 between
others.
 C3
axis
straight
down
 into
paper.
 LUMO,
anGbonding.
 NoGce
nodes
of
 electron
density
 between
P
atoms.
 ...
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This note was uploaded on 01/03/2012 for the course CH 102 taught by Professor Hill,m during the Fall '08 term at Caltech.

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