Glossary

Aluminum (chemical symbol Al, atomic number 13) is a lightweight, silvery-white metal known for its low density, strength-to-weight ratio, corrosion resistance, and high electrical and thermal conductivity. It is the most abundant metal in the Earth’s crust, making up about 8% of its mass, and is the second most widely used metal in the world, after steel.

In its pure form, aluminum is soft, ductile, and nonmagnetic, but it becomes much stronger when alloyed with other elements such as magnesium, silicon, copper, zinc, and manganese. These alloys are used extensively across industries because they combine lightness with strength and durability.

One of aluminum’s most important properties is its natural corrosion resistance. When exposed to air, it forms a thin, protective layer of aluminum oxide (Al₂O₃) on its surface that prevents further oxidation. This makes it ideal for applications in aerospace, automotive, construction, and marine environments.

Because it is both lightweight and strong, aluminum is used in aircraft and spacecraft structures, vehicle frames, bridges, and building facades. It’s also highly conductive, making it a common material for power lines, electronics, and heat exchangers. Additionally, it’s non-toxic and impermeable, which makes it perfect for food packaging, beverage cans, and kitchen utensils.

Aluminum is extracted primarily from bauxite ore, which is refined into alumina (aluminum oxide) and then reduced to metallic aluminum using the Hall–Héroult electrolytic process. This process is energy-intensive, which is why aluminum recycling is so valuable—recycling aluminum requires only about 5% of the energy needed to produce new metal.