|
|
|
Aluminium
......................................................................................................................................................................................................................................................................................................................
Aluminium is a soft, lightweight, malleable metal with appearance
ranging from silvery to dull gray, depending on the surface roughness.
Aluminium is nontoxic, nonmagnetic, and nonsparking. It is also
insoluble in alcohol, though it can be soluble in water only in certain
forms. The yield strength of pure aluminium is 7–11 MPa, while aluminium
alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium
has about one-third the density and stiffness of steel. It is ductile,
and easily machined, cast, and extruded.
Corrosion resistance is excellent due to a thin surface layer of
aluminium oxide that forms when the metal is exposed to air, effectively
preventing further oxidation. The strongest aluminium alloys are less
corrosion resistant due to galvanic reactions with alloyed copper
NATURAL OCCURANCE:
In the Earth's crust, aluminium is the most abundant (8.13%) metallic
element, and the third most abundant of all elements (after oxygen and
silicon). However, because of its strong affinity to oxygen, it is not
found in the elemental state but only in combined forms such as oxides
or silicates. Aluminium is found in the lithosphere. The most common
form it is found in is that of bauxite.
|
|
|
13 |
magnesium ←
aluminium → silicon |
|
B
↑
Al
↓
Ga |
Periodic table - Extended periodic table
|
|
General |
|
Name, symbol,
number |
aluminium, Al,
13 |
|
Chemical series |
poor metals |
|
Group, period,
block |
13, 3, p |
|
Appearance |
 |
|
Standard atomic
weight |
26.9815386(13) g•mol−1 |
|
Electron
configuration |
[Ne] 3s2 3p1 |
|
Electrons per
shell |
2, 8, 3 |
|
Physical properties |
|
Phase |
solid |
|
Density (near
r.t. |
2.70 g•cm−3 |
|
Liquid density
at m.p. |
2.375 g•cm−3 |
|
Melting point |
933.47 K
(660.32 °C, 1220.58 °F) |
|
Boiling point |
2792 K
(2519 °C, 4566 °F) |
|
Heat of fusion |
10.71 kJ•mol−1 |
|
Heat of
vaporization |
294.0 kJ•mol−1 |
|
Heat capacity |
(25 °C) 24.200
J•mol−1•K−1 |
|
Vapor pressure |
|
P/Pa |
1 |
10 |
100 |
1 k |
10 k |
100 k |
|
at T/K |
1482 |
1632 |
1817 |
2054 |
2364 |
2790 |
|
Atomic properties |
|
Crystal
structure |
face centered
cubic
0.40494 nm |
|
Oxidation
states |
3, 2 [1], 1 [2]
(amphoteric oxide) |
|
Electronegativity |
1.61 (Pauling
scale) |
|
Ionization
energies
(more) |
1st: 577.5
kJ•mol−1 |
|
2nd: 1816.7
kJ•mol−1 |
|
3rd: 2744.8
kJ•mol−1 |
|
Atomic radius |
125 pm |
|
Atomic radius
(calc.) |
118 pm |
|
Covalent radius |
118 pm |
|
Miscellaneous |
|
Magnetic
ordering |
paramagnetic |
|
Electrical
resistivity |
(20 °C) 26.50
nΩ•m |
|
Thermal
conductivity |
(300 K) 237
W•m−1•K−1 |
|
Thermal
expansion |
(25 °C) 23.1
µm•m−1•K−1 |
|
Speed of sound
(thin rod) |
(r.t.) (rolled)
5000 m•s−1 |
|
Young's modulus |
70 GPa |
|
Shear modulus |
26 GPa |
|
Bulk modulus |
76 GPa |
|
Poisson ratio |
0.35 |
|
Mohs hardness |
2.75 |
|
Vickers
hardness |
167 MPa |
|
Brinell
hardness |
245 MPa |
|
CAS registry
number |
7429-90-5 |
|
