Physical properties and uses of metals

Physical properties and uses of metalsChemical properties of metalsAlloysThe reactivity seriesRusting and its preventionExtraction of metals from oresExtraction of ironExtraction of aluminium (extended)

Introduction

Metals and non-metals have distinct physical and chemical properties due to differences in their atomic structure and bonding. Metals are chosen for specific applications based on their unique physical properties, such as density, conductivity, and resistance to corrosion. Understanding these properties helps explain why certain metals are used for particular purposes.

Physical properties of metals

Metals and non-metals differ significantly in their physical characteristics:

(a) Thermal Conductivity:

Metals:
- Excellent conductors of heat due to the presence of free-moving delocalized electrons.
- Example: Copper is used in cooking pans and heat exchangers for its high thermal conductivity.
Non-Metals:
- Poor conductors of heat as they lack delocalized electrons.
- Example: Polystyrene is used as an insulator in homes to reduce heat loss.

(b) Electrical Conductivity:

Metals:
- Good conductors of electricity because delocalized electrons can move freely, allowing an electric current to pass through.
- Example: Aluminum and copper are used in electrical wiring.
Non-Metals:
- Poor electrical conductors (insulators) as they do not have free electrons.
- Exception: Graphite, a non-metal, conducts electricity due to its delocalized electrons.

Metals:
- Malleable: Can be hammered or pressed into thin sheets without breaking.
- Ductile: Can be stretched into wires.
- Example: Gold and silver are used for making jewelry due to their malleability.
Non-Metals:
- Brittle: Tend to break or shatter when force is applied.
- Example: Sulfur and iodine crumble under pressure.

(d) Melting Points and Boiling Points:

Metals:
- Typically have high melting and boiling points due to strong metallic bonds.
- Example: Tungsten has one of the highest melting points and is used in light bulb filaments.
Non-Metals:
- Generally have lower melting and boiling points compared to metals.
- Example: Oxygen and nitrogen are gases at room temperature, indicating low boiling points.

The arrangement of ions and electrons in a pure, solid metal

Uses of metals

(a) Aluminium in the Manufacture of Aircraft

Reason: Aluminium has a very low density, making it lightweight.
Advantage: Aircraft need to be lightweight to reduce fuel consumption and increase efficiency during flight.
Example: Aluminium alloys are often used in the fuselage and wings of aircraft to maintain strength while minimizing weight.

(b) Aluminium in Overhead Electrical Cables

Reason:
- Low density: Reduces the overall weight of the cable, which is critical for spanning long distances.
- Good electrical conductivity: Ensures efficient transmission of electricity with minimal energy loss.
Advantage: The combination of lightness and conductivity makes aluminium ideal for use in high-voltage power lines.
Example: Aluminium is often used with a steel core in overhead cables to add strength while maintaining its lightweight properties.

Reason: Aluminium is highly resistant to corrosion because it forms a protective oxide layer on its surface when exposed to air.
Advantage:
- Protects food from contamination.
- Non-reactive with acidic or basic food substances.
Example: Aluminium foil and cans are used to store beverages and food items, keeping them fresh for extended periods.

(d) Copper in Electrical Wiring

Reason:
- Excellent electrical conductivity: Allows electric current to flow efficiently.
- Ductility: Can be easily drawn into thin wires without breaking.
Advantage: Copper wires ensure minimal energy loss during electrical transmission and are easy to shape and install.
Example: Copper is the standard material used for wiring in homes, appliances, and electronic devices.

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