Question

Almost all metals in nature are found as ionic compounds in ores instead of being in the pure state. Why? What must be done to a sample of ore to obtain a metal substance that has desirable properties?

Short answer

Metals are found as ionic compounds in ores because they are chemically active and tend to lose electrons, forming positive ions (cations) that bond with non-metals, creating more stable compounds. To obtain a metal substance with desirable properties from its ore, the process typically involves ore preparation, concentration, extraction, purification, and optionally, alloying.

Step-by-step solution

Reason for metals being found as ionic compounds

Metals are typically found as ionic compounds in nature because they are chemically active, meaning they tend to lose electrons to form positive ions (cations). When a metal atom loses electrons, it becomes positively charged and forms an ionic bond with a non-metal that gains the electrons. The strong electrostatic forces between the oppositely charged ions form an ionic compound. These ionic compounds are more stable and lower in energy than the pure metal atoms, making them the most common form of metal found in nature.

Obtaining metal substance from ore

To obtain a metal substance with desirable properties from its ore, the following steps are usually performed: 1. **Ore preparation**: First, the ore is mined and crushed into a fine powder to increase the surface area for further processing. This makes it easier for the chemical reactions to take place during the extraction process. 2. **Concentration**: The pulverized ore is then concentrated to separate the metal-containing compound from other impurities. This can be done through techniques like froth flotation, magnetic separation, or gravity separation. The choice of method depends on the nature of the ore and the metal to be extracted. 3. **Extraction**: After the concentration, the metal needs to be extracted from the ore. For metals that are less reactive, like gold or copper, the extraction is done by means of chemical reactions, such as reduction or oxidation. In case of more reactive metals, like aluminum or sodium, electrolysis is applied, where an electric current is passed through a molten ionic compound, causing the metal ions to gain electrons and deposit on the cathode as pure metal. 4. **Purification**: The extracted metal might still contain some impurities that can affect its properties. To obtain a metal substance with desirable properties, it needs to be purified further. Common purification techniques include electrolytic refining, zone refining, and fractional crystallization. 5. **Alloying (optional)**: In some cases, the desirable properties can be achieved by creating an alloy, which is a mixture of two or more metals. Alloying is done by melting the pure metal and adding the desired elements to the molten metal. After cooling, the alloy exhibits properties that are different from those of the individual metals. By following these steps, we can obtain a metal substance with desirable properties from a sample of ore.