Properties and Uses of Transition Metals

Transition metals possess several distinctive properties:

• Good conductors of electricity and heat
• Shiny appearance
• Form colored compounds
• High densities
• Malleable and strong

Specific examples include:

1. Iron: Malleable and strong, used in buildings and bridges.
2. Copper: Ductile and an excellent conductor of electricity, used for electrical wiring.
3. Aluminum: Used in household mirrors.
4. Silver: More reflective than aluminum, used as a coating for mirrors in infrared telescopes.

Highlight: The unique properties of transition metals make them invaluable in various applications, from construction to advanced scientific instruments.

Oxidation, Reduction, and Corrosion

Oxidation and reduction are key chemical processes in metal reactions:

Definition: Oxidation is the process of adding oxygen to a substance or the loss of electrons.

Definition: Reduction is the removal of oxygen from a compound or the gain of electrons.

Example: Iron oxide + carbon → Iron + carbon dioxide (carbon acts as the reducing agent)

The oxidation of iron results in corrosion, a significant problem for iron and steel structures.

Highlight: The more reactive a metal is, the quicker it will oxidize.

To extract a metal from its oxide, we need to remove the oxygen through a reduction process. This is crucial in metal extraction and processing.

Vocabulary: Reducing agent - A substance that removes oxygen from a compound in a chemical reaction.

Understanding these processes is essential for preventing corrosion and extracting metals efficiently from their ores.

Biological Methods of Metal Extraction

Two main biological methods for extracting metals from ores are bioleaching and phytoextraction.

Bioleaching:

Definition: Bioleaching is a process that uses bacteria to extract metals from low-grade ores.

Highlight: How is bioleaching used to extract copper from low grade ores? Bacteria produce a solution containing copper ions called leachate. Copper is then extracted from the leachate by displacement and purified by electrolysis.

Phytomining:

Definition: Phytomining involves using plants to absorb metal compounds from soil, which are then harvested to extract the metals.

Advantages of biological extraction methods:

• No harmful gases produced
• Less environmental damage
• Conserves supplies of higher-grade ores
• Does not require high temperatures

Disadvantages of bioleaching and phytomining:

• Slow process
• Can be more expensive
• Dependent on weather conditions (for phytomining)
• May produce toxic substances and sulfuric acid, potentially damaging the environment

Highlight: Both bioleaching and phytomining offer more environmentally friendly alternatives to traditional mining methods, but they come with their own set of challenges.