As a subject matter expert in the field of chemistry, I'd like to delve into the fascinating world of metal reactivity with oxygen. It's a complex subject that encompasses a range of reactions, from the rapid and explosive to the slow and almost imperceptible. The reactivity of metals with oxygen is a fundamental aspect of their chemical behavior and is determined by their position in the reactivity series, which is a list of metals arranged in order of decreasing reactivity.

At one end of the spectrum, we have the most reactive metals, such as potassium, sodium, and lithium. These metals are so reactive that they can ignite spontaneously in air and are stored under oil to prevent this. They react with oxygen almost instantaneously, forming oxides that can vary from simple oxides to peroxides and superoxides, depending on the metal and the conditions of the reaction.

Moving down the reactivity series, we encounter metals like calcium and magnesium. These are less reactive than the alkali metals but still react with oxygen at room temperature, albeit more slowly. The oxides formed by these metals are typically basic in nature and can be used in various industrial applications.

As we progress further down the series, we come to metals that are less reactive with oxygen. Metals such as copper and mercury are examples of this. Copper, for instance, does not react with oxygen at room temperature but can form an oxide layer when heated. This layer can protect the underlying metal from further oxidation, which is why copper objects can develop a green patina over time. Mercury, on the other hand, is unique in that it is a liquid at room temperature and reacts with oxygen to form mercuric oxide, which is a reddish-brown powder.

Now, to address the question at hand, the metal that is least reactive with oxygen and does not react with it when heated is gold. Gold is a noble metal and is known for its resistance to oxidation and corrosion. This is due to the stability of its electron configuration and the strength of the metallic bonds within the gold atoms. Gold does not form an oxide layer even when heated in air, which is why it is often used in applications where resistance to oxidation is crucial, such as in jewelry and electronics.

In summary, while most metals will react with oxygen to some extent, the rate and nature of these reactions can vary widely. Gold stands out as the metal that is least likely to react with oxygen, even under heat, making it a unique and valuable material in many respects.

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Metals such as potassium, sodium and lithium react with oxygen very quickly. Calcium and magnesium are slightly less reactive and react with oxygen less quickly. Metals like copper and mercury react with oxygen very slowly and need to be heated continuously in order to see this happening.read more >>