Question

Why are the elements of group 11 called coinage metals?

Answer 1

Hint: Group 11 in the modern periodic table belongs to the d-block and it contains elements like copper (atomic number = 29), silver (atomic number = 47) and gold (atomic number = 79).

Complete step by step solution:
The coinage metals comprise those metallic chemical elements which have historically been used as components in alloys used to mint coins.
Since 600 BC, coins have been the most universal embodiment of money. These first coins were made of electrum, a naturally occurring yellow mixture of gold and silver that was further alloyed with silver and copper.
Historically, most coinage metals are from the three nonradioactive members of group 11 of the modern periodic table: copper, silver and gold, the copper usually being augmented with tin and often other metals to form bronze. Gold, silver and bronze or copper were the coinage metals of the ancient world and post-medieval coins.
The reason these metals are used in traditional coinage is due to their abundance compared to other metals. However, coins were also made from other relatively common metals such as iron, or bronze, which is a copper alloy with Tin, or sometimes Zinc or Aluminium. These metals are somewhat less reactive and are often found naturally in oxide form.
Elements like gold and silver are also less likely to tarnish, making them last longer than metals like Magnesium, which would revert back into their original state within a relatively short period of time, especially when they are wet. Over time, gold and silver coins were just found to be the most effective at retaining their value. While copper coins oxidized over years and years, it was a relatively common material, and easily recyclable, so it was an effective low-value currency.

Note: Since a number of metals have been used to make "demonstration coins" which have never been used to make monetized coins for any nation-state, the term coinage metal for the only group 11 is not a perfect definition. Some of these elements would make excellent coins in theory like zirconium, but their status as coin metals is not clear.