Gold is a precious metal. Many people buy it for the purpose of preserving and appreciating its value. But what is disturbing is that some people find their gold bars or commemorative gold coins rusted.


Pure gold will not rust

Most metals react with oxygen to form metal oxides, which we call rust. But as a precious metal, gold does not rust. Why? This is an interesting question. We need to solve the mystery from the elemental properties of gold.

In chemistry, oxidation reaction is a chemical process in which a substance loses electrons and becomes positive ions. Because of the high content of oxygen in nature, it is easy to obtain electrons from other elements to form oxides. Therefore, we call this process oxidation reaction. The ability of oxygen to obtain electrons is certain, but the possibility of each element losing electrons is different, which depends on the ionization energy of the outermost electrons of the element.

Atomic structure of gold

Gold has strong oxidation resistance. As a transition metal, its first ionization energy is as high as 890.1kj/mol, second only to mercury (1007.1kj/mol) on its right. This means that it is extremely difficult for oxygen to capture an electron from gold. Gold not only has higher ionization energy than other metals, but also has high atomization enthalpy due to unpaired electrons in its 6S orbit. The atomization enthalpy of gold is 368kj / mol (mercury is only 64kj / mol), which means that gold has stronger metal binding force, and gold atoms are strongly attracted to each other, while mercury atoms are not strongly attracted to each other, so it is easier to be drilled by other atoms.

Post time: Sep-01-2022