(From the Latin alumen, "alum") A silvery, lightweight, easily worked, metallic chemical element that resists corrosion and is found abundantly, but only in combination.

Symbol: Al
Atomic number: 13
Atomic weight: 26.981538
Density (at room temperature and pressure): 2.70 g/cc
Melting point: 660.32°C
Boiling point: 2,519°C
Valence: +3
Ground state electron configuration: [Ne]3s23p1

Silicon Symbol: Al
Atomic Number: 13
Boiling Point: 2740 K
Melting Point: 933.5 K
Density at 300 K: 2.70 g/cm3
Covalent radius: 1.18
Atomic radius: 1.82
Atomic volume: 10.0 cm3/mol
First ionization potental: 5.986 V
Specific heat capacity: 0.90 J g-1 K-1
Thermal conductivity: 237 W m-1 K-1
Electrical conductivity: 37.7 106 Ω-1 m-1
Heat of fusion: 10.7 kJ/mol
Heat of vaporization: 290.8 kJ/mol
Electronegativity: 1.61 (Pauling's)

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To the Periodic Table

Aluminium has low density (is light), is strong and is corrosion-resistant.

Useful properties

  • Lightweight (low density).
  • It can be bent and shaped into, say, car body panels.
  • It's strong and rigid when required.
  • It doesn't corrode due to a protective layer of oxide which always quickly covers it.
  • It's a good conductor of heat and electricity.
It's not as strong as steel, however, and is a bit more expensive.

Common uses-

  • Ladders.
  • Aeroplanes.
  • Car body panels.
  • Drink cans. Tin-plated steel ones can rust if damaged.
  • Greenhouses and window frames.
  • Power cables.

Aluminum is also a fairly recent metal. That is to say, it only became available to humans recently. Although it is abundant in nature, it never occurs naturally in its metallic form. It was first hypothisized to exist in 1808 by Sir Humphrey Potter. It was only then that people started to refine aluminum ores to make metallic aluminum. Since it was rare, it was also expensive (about the price of silver) until 1886, when Charles Martin Hall began using electricity to refine the aluminum metal. This led to the eventual inexpensiveness of aluminum that we know today. Unfortunately, it would take a little while for a market to appear for this "new" metal.

Why do Americans spell this word differently than other people do?

Because we do what chemists tell us.

In 1807 Sir Humphry Davy discovered aluminum, and named it with only one i . The International Union of Pure and Applied Chemistry soon decided to add the extra i, to parallel the endings of sodium, potassium and other element names. The two-i spelling (aluminium) was the standard throughout the world for a time, even in the USA. (This explains why Webster 1913 has the two-i spelling as standard.) But in 1925 the American Chemical Society officially reverted to aluminum, and the one-i spelling has been standard in the US since. Which is to say, aluminum is not a misspelling of aluminium, and it's not a degradation of a traditional "aluminium" spelling. Instead, the American spelling is the earlier spelling. (And, contrary to what my British friends think, Americans aren't mispronouncing the word -- we spell it differently, and that's why we say it differently.)

Update: Redalien tells me that Davy originally named the element alumium (no "in"), which conforms with the common "ium" ending pattern. Then Davy changed it to the current U.S. spelling, then the IUPAC changed it to the current spelling accepted outside the U.S. So Davy was even more odd and contrary than I thought at first!

Aluminum is the most plentiful metal in the Earth's crust. Of the elements in Group 13 (of the Periodic Table), aluminum has the most practical uses. With three electrons in its outer level(valence shell), aluminum is less metallic than the other elements of Groups 1 and 2. In forming compounds, it tends to share electrons rather than form ions. It is also less reactive than the elements of groups 1 and 2 metals. One aluminum compound, aluminum sulfate, is used in water purification, paper manufacture, and fabric dyeing. Large amounts of elemental aluminum are used to produce lightweight alloys for many items from soft drink cans to spacecraft.

A*lu"mi*num (#), n. [L. alumen. See Alum.] Chem.

The metallic base of alumina. This metal is white, but with a bluish tinge, and is remarkable for its resistance to oxidation, and for its lightness, pertaining a specific gravity of about 2.6. Atomic weight 27.08. Symbol Al.

Aluminum bronze or gold, a pale gold-colored alloy of aluminum and copper, used for journal bearings, etc.


© Webster 1913.

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