Question

The Group \(1 \mathrm{~B}\) metals, \(\mathrm{Cu}, \mathrm{Ag},\) and \(\mathrm{Au},\) are called coinage metals. What chemical properties make them especially suitable for making coins and jewelry?

Short answer

Coinage metals resist corrosion, are malleable, and have low chemical reactivity.

Step-by-step solution

Understand the Group 1B Metals

Group 1B of the periodic table consists of copper (\(\text{Cu}\)), silver (\(\text{Ag}\)), and gold (\(\text{Au}\)). These metals are known as the coinage metals due to their historical and ongoing use in minting coins and making jewelry.

Identify Chemical Properties

The main chemical properties that make Group 1B metals suitable for coins and jewelry are their resistance to corrosion and tarnish. These metals do not readily react with air or moisture, which ensures that they retain their appearance over time.

Examine Inertness to Chemicals

Coinage metals like copper, silver, and gold show low reactivity with most acids and environmental conditions due to their high standard electrode potentials. This quality helps them maintain their luster and integrity, crucial for coins and jewelry.

Consider Malleability and Ductility

In addition to chemical inertness, these metals are malleable and ductile. Malleability allows them to be shaped into various forms without breaking, while ductility enables them to be drawn into wires, both of which are essential for detailed designs in coins and jewelry.

Key concepts

Chemical Properties

The coinage metals, which include copper ( Cu ), silver ( Ag ), and gold ( Au ), exhibit distinct chemical properties that contribute to their suitability for coins and jewelry. One key property is their low reactivity with environmental factors such as air and moisture. This means that these metals do not easily tarnish, an important trait for maintaining a shiny appearance over time.
Another significant chemical property is their high standard electrode potential. This makes them relatively inert to many chemicals, including acids, a valuable attribute when designing durable coins and fine jewelry that remain intact under various conditions.

Corrosion Resistance

Corrosion resistance is a vital property of the coinage metals and it's what keeps them looking beautiful and shiny through the years. These metals are inherently resistant to corrosion, which means they aren't affected much by exposure to water or air.
Gold, in particular, is one of the least reactive metals and doesn't tarnish, while copper and silver can still resist corrosion better than many other metals. Silver might tarnish slightly over time due to reactions with sulfur compounds in the air, forming a thin layer of black tarnish, but this can be easily polished off.

• Gold: Excellent resistance, untouched by moisture or air.
• Silver: Slight tarnishing, can be polished.
• Copper: Better than many metals, but less resistant than gold.

Malleability

Malleability is a characteristic that describes how metals can be hammered or rolled into thin sheets without breaking. This trait is particularly beneficial for the coinage metals. Coins and jewelry often require intricate designs and detailed engravings. Due to their malleability, copper, silver, and gold can be crafted into various shapes and forms with great precision.
For instance, gold is incredibly malleable and can be beaten into sheets thin enough to be transparent, making it ideal for decorative purposes as well.

Ductility

Ductility refers to a metal's ability to be stretched into a wire. This is an essential property for creating not just coins, but also delicate pieces of jewelry that require fine detailing. Copper, silver, and gold display remarkable ductility, allowing them to be drawn into thin wires without breaking. This is crucial for producing detailed and complex designs in jewelry-making, where flexibility and precision are paramount.
Whether in the form of delicate chains or intricate components within a piece, their ductility ensures durability while maintaining an appealing design.