Commonly used hardware materials are made of five metals: gold, silver, copper, iron and aluminum.

1. The simple substance (free form) of gold is commonly known as gold. It is a popular precious metal and has been used as currency, value preservation and jewelry for many centuries.

In nature, gold appears as a single substance in gold nuggets or gold particles in rocks, underground veins and alluvial layers. Gold is also one of currency metals. The simple substance of gold is solid at room temperature, with high density, softness, brightness and corrosion resistance, and its ductility is second only to platinum.

2. Silver (Argentum) is a kind of transition metal. Chemical symbol Ag. Silver is one of the metals known and used in ancient times, and it is an important precious metal.

Silver exists as a simple substance in nature, but most of it exists in silver ore in the form of a chemical state. Silver has relatively stable physical and chemical properties, good thermal and electrical conductivity, soft quality and rich ductility. The reflectivity is extremely high, reaching over 99%. There are many important uses.

3. Copper is a transition element, chemical symbol Cu, English copper, atomic number 29. Pure copper is a soft metal, the surface is reddish orange with metallic luster when it is just cut, and its simple substance is purple-red.

Good ductility, high thermal conductivity and electrical conductivity, so it is the most commonly used material in cables and electrical and electronic components. It can also be used as a building material and can be composed of many alloys. Copper alloys have excellent mechanical properties and low resistivity. The most important ones are bronze and brass. In addition, copper is also a durable metal that can be recycled multiple times without compromising its mechanical properties.

4. Iron is a metal element with atomic number 26. The chemical formula of iron is Fe. Pure iron is white or silvery white with metallic luster. Melting point 1538℃, boiling point 2750℃, soluble in strong acid and medium strong acid, insoluble in water. Iron has 0, +2, +3, and +6 prices, of which +2 and +3 prices are more common, and +6 prices are rare.

5. Aluminum, silver-white light metal. There is malleability. Commodities are often made into rods, flakes, foils, powders, ribbons and filaments. It can form an oxide film to prevent metal corrosion in humid air. Aluminum powder can burn violently when heated in the air and emit a dazzling white flame.

It is easily soluble in dilute sulfuric acid, nitric acid, hydrochloric acid, sodium hydroxide and potassium hydroxide solution, but hardly soluble in water. The relative density is 2.70. Melting point is 660°C. The boiling point is 2327℃.