アルミニウムは金属か？

We see it in cans, windows, and planes—but is aluminum really a metal like iron or copper?

Yes, aluminum is a metal—specifically a lightweight, silvery-white metal in the boron group with excellent conductivity and corrosion resistance.

It’s one of the most abundant and widely used metals on Earth.

What defines a metal and is aluminum one?

Before labeling any element a metal, we need to know what makes something a “metal.”

A metal is defined by its ability to conduct electricity, have a shiny appearance, be malleable, ductile, and form positive ions. Aluminum meets all of these criteria.

Key Metallic Properties

Aluminum also shows metallic bonding, meaning its atoms share a "sea" of electrons—typical of metals.

Periodic Table Classification

Aluminum is in Group 13, next to boron and gallium. It sits clearly among the metals.

How is aluminum’s conductivity compared to other metals?

Electrical and thermal conductivity are major reasons metals are used in engineering—and aluminum performs well.

Aluminum is an excellent conductor of electricity and heat, second only to copper and silver among common metals.

電気伝導率

Aluminum’s conductivity is about 61% that of copper. However, it’s much lighter, making it better for weight-sensitive applications like:

• Power lines
• Electric vehicles
• Aircraft wiring

熱伝導率

Aluminum also transfers heat well. That’s why it’s used in:

• ヒートシンク
• Radiators
• Cookware

Why is aluminum versatile in industry?

Aluminum is everywhere—from soda cans to skyscrapers. Why?

Aluminum’s low density, corrosion resistance, formability, and recyclability make it extremely versatile across multiple industries.

軽量で丈夫

Aluminum is about one-third the weight of steel, yet strong enough for construction and transport. That’s why it’s used in:

• Airplanes
• Trains
• Automotive frames

耐食性

Its natural oxide layer prevents rust and degradation. That’s why it’s chosen for:

• 窓枠
• Marine parts
• 屋外看板

Easily Formed

You can:

• Extrude it into complex shapes
• Roll it into thin foil
• Mold it in casting

リサイクル可能

Aluminum is 100%リサイクル可能 without losing quality. Recycled aluminum uses 95% less energy than primary production.

How was aluminum classified historically?

Aluminum’s early history is strange. It was once more valuable than gold.

Historically, aluminum was difficult to extract and was once considered a precious metal before industrial processes made it widely available.

Early Discovery

Aluminum was first isolated in 1825 by Hans Christian ?rsted. However, it took until the late 1800s for practical methods to produce it affordably.

Napoleon’s Aluminum Cutlery

Napoleon reportedly reserved aluminum cutlery for his most honored guests—others got gold or silver. That’s how rare it was.

Hall-Héroult Process

In 1886, Charles Hall (USA) and Paul Héroult (France) discovered electrolysis of alumina in molten cryolite—making mass production possible.

That changed everything. By 1900, aluminum became common in manufacturing.

From Luxury to Utility

Aluminum shifted from being a rare lab curiosity to the backbone of modern industry in just 50 years.

結論

Aluminum is absolutely a metal—lightweight, conductive, corrosion-resistant, and industrially essential. Its unique properties and history make it one of the most valuable materials in the modern world.