Question

Gold Jewellery does not become dull. Why?

Answer 1

Hint: Understand what can cause the gold jewellery to become dull. Because gold is a metal so corrosion might be one among the reasons. In order to withstand corrosion, making the jewellery alloy in nature can be one among the factors. Additionally, Gold is also a noble metal.

Complete step-by-Step solution:
Gold is a dense lustrous yellowish coloured precious metal. It's a chemical element of atomic number 79. Gold is used especially in jewellery and decoration. Additionally, it is also used to guarantee the value of currencies.
The gold jewellery that we use is not made up of just gold only, i.e., it is not pure. The gold jewellery that we use or wear are actually alloy by nature. In every gold jewellery, the measure of purity of gold is done in terms of carat.
Alloy is a metal made up by combining two or more metallic elements. This is done in order to provide greater strength or resistance to corrosion.
Now, corrosion is the process in which a solid, especially a metal, is eaten away or say changed by a chemical reaction. Corrosion leads to rust forming up on the metal. Rust is nothing but a reddish-brown flaky coating on metal. In other words, it is hydrated iron oxide which causes iron to react with oxygen and water.
But Gold is a noble metal in the periodic table having atomic number 79 also. Noble metals are by their chemical nature inert and hence do not get corroded in the natural or industrial environment. This happens because gold does not react with oxygen in the atmosphere.
Therefore, gold jewellery does not become dull because it does not react with oxygen in the atmosphere as it is inert by nature. Additionally, the process of making gold jewellery by alloying also helps the gold withstand any other possibility of it reacting with atmospheric oxygen.
And hence there is no formation of any layer on its surface. So, no formed rust layer on the surface leads to the gold jewellery not becoming dull.

Note: Students usually tend to skip either of the two conditions supporting the non-corrosive behaviour of the gold jewellery. So, it is important to understand both factors. Also, with excessive time and exposure to perfumes, deodorant and acid-based cleaning solutions and human sweat can cause the gold jewellery to tarnish. This should be clearly understood as well.