Aluminum

The name aluminum comes from the Latin word alumen, which refers to alum, a type of aluminum sulfate. Alum has been used since at least the 5th century BCE! In ancient times, people used it mainly for two things: cleaning water and helping dyes stick to fabric. It was super useful for making sure water was clear and for keeping colors on clothes bright. Today, alum is also used in medicine and cosmetics, like in antiperspirants and to stop bleeding from small cuts, such as those you might get from shaving.

In the 1700s, scientists started to suspect that alum contained a new metal, which we now know as aluminum. In 1789, French chemist Antoine Lavoisier published a theory that alum contained this mystery metal. A few years later, British scientist Sir Humphry Davy tried to isolate aluminum by using electricity (a method called electrolysis), but that didn’t work. In 1825, Danish physicist Hans Christian Øersted finally managed to isolate aluminum—kind of. He heated an aluminum salt with potassium. The aluminum he got was still impure. Two years later, Friedrich Wöhler, a German chemist, improved Øersted’s process and succeeded in making pure aluminum! At first, it was just a gray powder, but by 1845, Wöhler figured out how to shape it into solid metal balls.

Interestingly, Davy was the one to suggest the name aluminum, but there was some confusion over how to spell it. Some early work used "aluminum" (ending in -um like platinum), while others used "aluminium" (-ium like most other metals). In the United States, people mostly preferred “aluminium” until around 1895, when “aluminum” became the more popular spelling. The debate wasn’t officially settled until 1925, when the American Chemical Society decided to go with “aluminum.”

Internationally, however, the debate continued. In 1990, the International Union of Pure and Applied Chemistry (IUPAC) declared that "aluminium" was the official name. But in 1993, they agreed that "aluminum" was also acceptable, meaning both spellings are correct today, depending on where you are.

Pure aluminum, a silvery-white metal, possesses many desirable characteristics. It is light, nonmagnetic, non-sparking, and electrically conductive. It can be shaped easily. It is the second most malleable metal and the sixth most ductile.  

It does not rust. In air, it forms a thin, protective, corrosion-resistant oxide layer on its surface. This layer is shiny and reflective and does not tarnish as it would for silver. 

Aluminum is a very lightweight metal. It has about one-third the density of steel. This makes it especially useful for applications where weight is a major concern. Aircraft and rocket frames are key examples, but cars, trucks, train cars, ships, and bicycles use aluminum, too. However, it is a soft metal, so it’s usually alloyed with small amounts of another metal to improve its strength for these transportation applications. The alloying metals include copper, magnesium, silicon, manganese, and zinc.

Aluminum is considered highly conductive, but its conductivity is only about 60 percent that of copper. Yet it is used in electrical transmission lines because of its light weight. It is also used in other electrical machinery (motors, generators, transformers, etc.).

Aluminum is inexpensive but more expensive than steel. So, in building construction, it is used when low weight or corrosion resistance is important, such as for doors, window frames, aluminum siding, gutters, and metal roofs.

It is extensively used for kitchen utensils, packaging (soda cans, aluminum foil), and lightweight components of consumer products. Many laptop computers, smartphones, and smartwatches have aluminum exteriors—often recycled from used soda cans. Aluminum is infinitely recyclable.

Aluminum is the second most widely used metal after iron. 

The aluminum compounds of greatest importance are the oxide, sulfate, and the soluble sulfate with potassium (alum).

Aluminum is the third most abundant element in Earth’s crust, after oxygen and silicon, and the most abundant metal. It makes up 8 percent of the crust by mass. The most common way to obtain it commercially is to mine it from bauxite, a sedimentary rock.