Question

Which of the following metals is not found in the free state in nature: \(\mathrm{Ag}, \mathrm{Cu}, \mathrm{Zn}, \mathrm{Au}, \mathrm{Pt} ?\)

Short answer

Zinc (\(\mathrm{Zn}\)) is not found in the free state in nature.

Step-by-step solution

Understand the Concept of Free State

Metals that appear in the free state in nature are usually unreactive. They do not form compounds easily and can be found as pure elemental metals. Common examples include noble metals like gold and platinum.

Evaluate Each Metal

Evaluate each metal in the list to determine if it is typically found in the free state in nature. - \(\mathrm{Ag} \ (Silver)\) and \(\mathrm{Au} \ (Gold)\) are noble metals, often found in free state due to their low reactivity.-\(\mathrm{Cu} \ (Copper)\) is also often found in native state as nuggets in some locations.- \(\mathrm{Pt} \ (Platinum)\) is a noble metal and is found in free state in its natural environment.- \(\mathrm{Zn} \ (Zinc)\) is more reactive and typically not found in free state as it forms compounds readily.

Conclude Based on Evaluation

Based on the evaluation in Step 2, determine which metal does not occur naturally in the free state. From our observations, \(\mathrm{Zn} \ (Zinc)\) is the metal that is most reactive among the given options and not found in the free state in nature.

Key concepts

Noble metals

Noble metals are a unique group of metals known for their exceptional resistance to corrosion and oxidative damage. These metals are often found in their pure, elemental state in nature due to their low reactivity. This low tendency to form compounds allows them to stay "free" rather than being bonded with other elements easily. Some of the most well-known noble metals include:

• Gold (\(\mathrm{Au}\)
• Platinum (\(\mathrm{Pt}\)
• Silver (\(\mathrm{Ag}\)

These metals are precious not only for their beauty and luster but also due to their chemical properties that make them ideal for use in electronics, jewelry, and other high-value applications. In nature, they can often be found as nuggets or veins, when erosion processes expose these metals on the surface or within stream beds.

Reactivity of metals

The reactivity of metals is a key concept in understanding why some metals are found in nature in their native or free state while others are not. Reactivity refers to how easily a metal will engage in chemical reactions, forming compounds with other elements like oxygen, sulfur, and chlorine.

Highly reactive metals, such as sodium (\(\mathrm{Na}\)) and potassium (\(\mathrm{K}\)), are typically found as compounds rather than pure elements. Zinc (\(\mathrm{Zn}\)) falls into this category due to its moderate reactivity. It tends to form compounds because it readily reacts with other elements.

• Low reactivity means a metal is found more readily in a free state, like gold (\(\mathrm{Au}\)).
• High reactivity tends to keep metals as compounds in nature, like zinc (\(\mathrm{Zn}\)).

Understanding these differences helps in identifying which metals can be found in their natural, uncombined form.

Chemical compounds

Chemical compounds are substances formed when two or more elements chemically bond together, usually involving the transfer or sharing of electrons. Metals that are highly reactive will form compounds, which can be oxides, sulfides, chlorides, and many other forms based on the reacting elements.

For example, zinc (\(\mathrm{Zn}\)) readily forms compounds such as zinc oxide (\(\mathrm{ZnO}\)) because it reacts easily with oxygen in the air. This behavior of zinc and other similar metals is why they are generally not found in their free state.

• Compounds are formed due to high reactivity.
• Non-reactive metals, like the noble metals, resist compound formation.
• This explains why noble metals are seen as pure elements in nature.

The study of chemical compounds is essential for understanding not only why certain metals are not found in their elemental form but also how they can be extracted and purified for use.