[General | States | Energies | Oxidation & Electrons]
[Appearance & Characteristics | Reactions | Other Forms]
[Radius | Conductivity
| Abundance | History]
| Name |
Aluminum |
Symbol |
Al |
| Atomic number |
13 |
Atomic weight |
26.98154 |
| Density @ 293 K |
2.702 g/cm3 |
Atomic volume |
10.0 cm3/mol |
| Group |
Metal |
Discovered |
1825 |
| State (s, l, g) |
s |
| Melting point |
933.57 K |
Boiling point |
2740 K |
| Heat of fusion |
10.790 kJ/mol |
Heat of vaporization |
293.40 kJ/mol |
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| 1st ionization energy |
577.6 kJ/mole |
Electronegativity |
1.61 |
| 2nd ionization energy |
1816.6 kJ/mole |
Electron affinity |
42.6 kJ/mole |
| 3rd ionization energy |
2744.7 kJ/mole |
Specific heat |
0.90 J/gK |
| Heat atomization |
326 kJ/mole atoms |
| Shells |
2,8,3 |
Electron configuration |
[Ne] 3s2 3p1 |
| Minimum oxidation number |
0 |
Maximum oxidation number |
3 |
| Minimum common oxidation number |
0 |
Maximum common oxidation number |
3 |
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| Structure |
fcc: face-centered cubic |
Color |
silvery |
| Uses |
Al cans & foil,reflectors |
Toxicity |
|
| Hardness |
2.8 mohs |
Characteristics |
passivated: surface oxide |
| Reaction with air |
mild, w/ht =>Al2O3 |
Reaction with 6M HCl |
mild, =>H2, AlCl3 |
| Reaction with 6M HCl |
mild, =>H2, AlCl3 |
Reaction with 15M HNO3 |
passivated |
| Reaction with 6M NaOH |
mild, =>H2, [Al(OH)4]- |
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| Number of isotopes |
1 |
Hydride(s) |
AlH3 |
| Oxide(s) |
Al2O3 |
Chloride(s) |
AlCl3Al2Cl6 |
| Ionic radius (2- ion) |
pm |
Ionic radius (1- ion) |
pm |
| Atomic radius |
143 pm |
Ionic radius (1+ ion) |
pm |
| Ionic radius (2+ ion) |
pm |
Ionic radius (3+ ion) |
67.5 pm |
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| Thermal conductivity |
237 J/m-sec-deg |
electrical conductivity |
376.676 1/mohm-cm |
| polarizability |
8.3 A^3 |
| source |
Bauxite (oxide) |
rel. abund. solar system |
4.929 log |
| abundance earth's crust |
4.9 log |
cost, pure |
1.8 $/100g |
| cost, bulk |
0.12 $/100g |
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History:
(L. alumen,
alum) The ancient Greeks and Romans used alum in
medicine as an astringent, and as a mordant in
dyeing. In 1761 de Morveau proposed the name
alumine for the base in alum, and Lavoisier, in
1787, thought this to be the oxide of a still
undiscovered metal. Wohler is generally credited
with having isolated the metal in 1827, although
an impure form was prepared by Oersted two years
earlier. In 1807, Davy proposed the name alumium
for the metal, undiscovered at that time, and
later agreed to change it to aluminum. Shortly
thereafter, the name aluminium was adopted to
conform with the "ium" ending of most
elements, and this spelling is now in use
elsewhere in the world. Aluminium was also the
accepted spelling in the U.S. until 1925, at
which time the American Chemical Society
officially decided to use the name aluminum
thereafter in their publications. The method of
obtaining aluminum metal by the electrolysis of
alumina dissolved in cryolite was dicovered in
1886 by Hall in the U.S. and at about the same
time by Heroult in France. Cryolite, a natural
ore found in Greenland, is no longer widely used
in commercial production, but has been replaced
by an artificial mixture of sodium, aluminum, and
calcium fluorides. Aluminum can now be produced
from clay, but the process is not economically
feasible at present. Aluminum is the most
abundant metal to be found in the earth's crust
(8.1%), but is never found free in nature. In
addition to the minerals mentioned above, it is
found in granite and in many other common
minerals. Pure aluminum, a silvery-white metal,
possesses many desirable characteristics. It is
light, it is nonmagnetic and nonsparking, stands
second among metals in the scale of malleability,
and sixth in ductility. It is extensively used
for kitchen utensils, outside building
decoration, and in thousands of industrial
applications where a strong, light, easily
constructed material is needed. Although its
electrical conductivity is only about 60% that of
copper, it is used in electrical transmission
lines because of its light weight. Pure aluminum
is soft and lacks strength, but it can be alloyed
with small amounts of copper, magnesium, silicon,
manganese, and other elements to impart a variety
of useful properties. These alloys are of vital
importance in the construction of modern aircraft
and rockets. Aluminum, evaporated in a vaccum,
forms a highly reflective coating for both
visible light and radiant heat. These coating
soon form a thin layer of the protective oxide
and do not deteriorate as do silver coatings.
They have found application in coatings for
telescope mirrors, in making decorative paper,
packages, toys, and in many other uses. The
compounds of greatest importance are aluminum
oxide, the sulfate, and the soluble sulfate with
potassium (alum). The oxide, alumina, occurs
naturally as ruby, sapphire, corundum, and emery,
and is used in glassmaking and refractories.
Synthetic ruby and sapphire have found
application in the construction of lasers for
producing coherent light.
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