Aluminium

	magnesium ← aluminium → silicon
Appearance
	silvery gray metallic; ; ; Spectral lines of aluminium
General properties
Name, symbol, number	aluminium, Al, 13
Pronunciation	UK i/ˌæljʉˈmɪniəm/; AL-ew-MIN-ee-əm; U.S. i/əˈljuːmɨnəm/; ə-LEW-mi-nəm
Element category	other metal
Group, period, block	13, 3, [[{{{block}}}-block\|{{{block}}}]]
Standard atomic weight	26.9815386(13) g/mol
Electron configuration	[Ne] 3s2 3p1
Electrons per shell	2, 8, 3 (Image)
Physical properties
Phase	solid
Density (near r.t.)	2.70 g/cm3
Liquid density at m.p.	2.375 g/cm3
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
Heat of vaporization	294.0 kJ/mol
Specific heat capacity	(25 °C) 24.200 J/(mol·K)
Vapor pressure
Atomic properties
Oxidation states	3, 2, 1; (amphoteric oxide)
Electronegativity	1.61 (Pauling scale)
Ionization energies;	1st: 577.5 kJ/mol
	2nd: 1816.7 kJ/mol
	3rd: 2744.8 kJ/mol
Atomic radius	143 pm
Covalent radius	121±4 pm
Van der Waals radius	184 pm
Miscellanea
Crystal structure	face-centered cubic
Magnetic ordering	paramagnetic
Electrical resistivity	(20 °C) 28.2 nΩ·m
Thermal conductivity	(300 K) 237 W/(m·K)
Thermal expansion	(25 °C) 23.1 µm/(m·K)
Speed of sound (thin rod)	(r.t.) (rolled) 5,000 m/s
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
Most stable isotopes
	Main article: Isotopes of aluminium
	v; t; e;

Aluminium (American spelling: aluminum) is a chemical element. The symbol for aluminium is Al, and its atomic number is 13. Aluminium is the most abundant metal.

Properties[change | change source]

Aluminium is a very good conductor of electricity and heat. It is light and strong. It can be hammered into sheets (malleable) or pulled out into wires (ductile). It is a highly reactive metal, although it is corrosion resistant.

Aluminium prevents corrosion by forming a small, thin layer of aluminium oxide on its surface. This layer protects the metal by preventing oxygen from reaching it. Corrosion can not occur without oxygen. Because of this thin layer, the reactivity of aluminium is not seen.

Occurrence and preparation[change | change source]

Pure aluminium is made from bauxite, a kind of rock that has aluminium oxide and many impurities. The bauxite is crushed and reacted with sodium hydroxide. The aluminium oxide dissolves. Then the aluminium oxide is dissolved in liquid cryolite, a rare mineral. Cryolite is normally produced artificially though. The aluminium oxide is electrolyzed to make aluminium and oxygen.

Aluminium was once considered a precious metal that was even more valuable than gold. This is no longer true because, as technology improved, it became cheaper and easier to make pure metal.

Compounds[change | change source]

Aluminium forms chemical compounds in the +3 oxidation state. They are generally unreactive. Aluminium chloride and aluminium oxide examples. Very rarely are compounds in the +1 or +2 oxidation state.

Uses[change | change source]

Many things are made of aluminum. Much of it is used in overhead power lines. It is also widely used in window frames and aircraft bodies. It is found at home as saucepans, soft drink cans, and cooking foil. Aluminium is also used to coat car headlamps and compact discs.

Pure aluminium is very soft, so a harder metal is almost always added. The harder metal is usually copper. Copper/aluminium alloys are to make ships, because the aluminium prevents corrosion, and the copper prevents barnacles.

Aluminium compounds are used in deodorants, water processing plants, food additives, and antacids.

Recycling[change | change source]

Since aluminium needs to be made by electrolysis, it requires a very large amount of electrical power. Recycling aluminium would be much cheaper. That's why recycling plants were opened. The cost of recycling aluminium is much less than the cost of making it from bauxite.

Toxicity[change | change source]

Aluminium is not used in the human body, although it is very common. People debate whether its use in deodorants and water treatment is healthy. Aluminium ions slow down plant growth in acidic soils. Aluminium may be a factor in Alzheimer's disease (a disease when the brain stops working and the patient is confused).^[4]^[5] But the Alzheimer's Society says overwhelming medical and scientific opinion is that studies have not convincingly demonstrated a causal relationship between aluminium and Alzheimer's disease.^[6]