(From the Greek language phôs meaning "light", and
phoros meaning "bearer"), is the
chemical element in the
periodic table that has the symbol P and
atomic number 15. A
multivalent
nonmetal of the
nitrogen group, phosphorus is commonly found in
inorganic phosphate rocks and in all living cells. Due
to its high reactivity, it is never found as a free
element in nature. It emits a faint glow upon exposure
to
oxygen (hence its Greek derivation and the
Latin meaning 'morning star'), occurs in several
allotropic forms, and is an essential element for
living organisms. The most important commercial use of
phosphorus is in the production of
fertilizers. It is also widely used in
explosives, friction
matches,
fireworks,
pesticides,
toothpaste, and
detergents.
Notable characteristics:Common
phosphorus forms a waxy white solid that has a characteristic
disagreeable smell similar to that of garlic.
Pure forms of the element are colorless and transparent. This
nonmetal is not
soluble in
water,
but it is soluble in
carbon disulfide. Pure phosphorus ignites spontaneously in air and
burns to produce
phosphorus pentoxide.
¡@Applications:
Concentrated
phosphoric acids, which can consist of 70% to 75% P2O5
are very important to
agriculture and farm production in the form of
fertilizers. Global demand for fertilizers led to
large increases in
phosphate (PO43-) production
in the second half of the
20th century. Other uses;
- Phosphates are utilized in the making of special
glasses that are used for
sodium lamps.
- Bone-ash,
calcium phosphate, is used in the production of
fine china .
-
Sodium tripolyphosphate made from phosphoric
acid is used in laundry detergents in several
countries, and banned for this use in others.
- Phosphoric acid made from elementary phosphorus
is used in food applications such as soda beverages.
The acid is also a starting point to make food grade
phosphates. These include mono-calcium phosphate
which is employed in
baking powder and
sodium tripolyphosphate and other sodium
phosphates. Among other uses, these are used to
improve the characteristics of processed meat and
cheese. Others are used in toothpaste.
Trisodium phosphate is used in cleaning agents
to
soften water and for preventing pipe/boiler tube
corrosion.
- Phosphorus is widely used to make
organophosphorus compounds, through the
intermediates
phosphorus chlorides and
phosphorus sulphide. These have many
applications, including in
plasticizers,
flame retardants,
pesticides,
extraction agents, and water treatment.
- This element is also an important component in
steel production, in the making of
phosphor bronze, and in many other related
products.
-
White phosphorus is used in
military applications as
incendiary bombs, for
smoke-screening as smoke pots and
smoke bombs, and in
tracer ammunition.
- Red phosphorus is essential for manufacturing
matchbook strikers, flares, and, most notoriously,
methamphetamine.
- In trace amounts, phosphorus is used as a
dopant for
N-type semiconductors.
- 32P and 33P are used as
radioactive tracers in biochemical laboratories (see
#Isotopes).
¡@ |
15 |
silicon
¡öphosphorus¡÷
sulfur |
|
General |
Name,
Symbol,
Number |
phosphorus, P, 15 |
Chemical series |
nonmetals |
Group,
Period,
Block |
15,
3, p |
Appearance |
waxy white/ red/
black/ colorless |
Atomic mass |
30.973762(2)
g/mol |
Electron configuration |
[Ne] 3s2
3p3 |
Electrons per
shell |
2, 8, 5 |
Physical
properties |
Phase |
solid |
Density (near
r.t.) |
(white) 1.823 g/cm³ |
Density (near
r.t.) |
(red) 2.34 g/cm³ |
Density (near
r.t.) |
(black) 2.69 g/cm³ |
Melting point |
(white) 317.3
K
(44.2 ¢XC,
111.6 ¢XF) |
Boiling point |
550 K
(277 ¢XC,
531 ¢XF) |
Heat of fusion |
(white) 0.66
kJ/mol |
Heat of vaporization |
12.4
kJ/mol |
Heat capacity |
(25 ¢XC) (white)
23.824 J/(mol¡PK) |
Vapor pressure (white)
P/Pa |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T/K |
279 |
307 |
342 |
388 |
453 |
549 |
|
Vapor pressure (red)
P/Pa |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T/K |
455 |
489 |
529 |
576 |
635 |
704 |
|
Atomic
properties |
Oxidation states |
¡Ó3, 5, 4
(mildly acidic
oxide) |
Electronegativity |
2.19 (Pauling
scale) |
Ionization energies |
1st: 1011.8
kJ/mol |
2nd: 1907 kJ/mol |
3rd: 2914.1 kJ/mol |
Atomic radius |
100 pm |
Atomic radius (calc.) |
98
pm |
Covalent radius |
106
pm |
Van der Waals radius |
180
pm |
Miscellaneous |
Magnetic ordering |
no data |
Thermal conductivity |
(300 K) (white)
0.236
W/(m¡PK) |
Bulk modulus |
11 GPa |
CAS registry number |
7723-14-0 |
Notable
isotopes |
Main article:
Isotopes of phosphorus
iso |
NA |
half-life |
DM |
DE (MeV) |
DP |
31P |
100% |
P is
stable with 16
neutrons |
32P |
syn |
14.28
d |
£]- |
1.709 |
32S |
33P |
syn |
25.3
d |
£]- |
0.249 |
33S |
|
¡@ |
|