Paripurnanand

Materials – Metals and Non-Metals

Materials around us are used for many different purposes. Some materials are used for making utensils, buildings, machines, and electrical wires. Others are used in medicines, fertilizers, and fuels. Many of these materials are classified as metals and non-metals.

These two groups have different physical and chemical properties that determine how they are used in daily life. Understanding the differences between metals and non-metals helps us choose the right material for specific purposes.

1. What are Metals?

Metals are substances that are usually hard, shiny, and strong. They are good conductors of heat and electricity and are widely used in construction, transportation, and electrical appliances.

Examples of metals:

• Iron
• Copper
• Aluminium
• Gold
• Silver
• Zinc

Most metals are found in nature in the form of ores, which are compounds of metals mixed with other materials such as soil and rock.

2. Physical Properties of Metals

Lustre

Metals have a shiny surface called metallic lustre. Because of this property, metals like gold and silver are used in jewelry.

Hardness

Most metals are hard and strong. However, metals like sodium and potassium are soft.

Malleability

Metals can be hammered into thin sheets. Gold is the most malleable metal.

Ductility

Metals can be drawn into thin wires. Copper and aluminium are used for electrical wires.

Conductivity

Metals conduct heat and electricity efficiently.

Sonorous Nature

Metals produce a ringing sound when struck. Therefore, they are used to make musical instruments.

3. What are Non-Metals?

Non-metals are substances that generally do not have the properties of metals. They are usually dull, brittle, and poor conductors of heat and electricity.

Examples:

• Carbon
• Oxygen
• Nitrogen
• Sulphur
• Phosphorus
• Chlorine

Non-metals are important in many biological and chemical processes.

4. Physical Properties of Non-Metals

• Lack of Lustre: Non-metals usually appear dull.
• Brittleness: They break easily when hammered.
• Poor Conductivity: They do not conduct heat or electricity well.
• Non-Sonorous: They do not produce ringing sounds.
• Low Density: Most non-metals are lighter than metals.

An important exception is graphite, which can conduct electricity.

5. Uses of Metals

• Construction: Iron and steel are used for buildings and bridges.
• Electrical Wiring: Copper and aluminium are used for wires.
• Cooking Utensils: Aluminium and steel conduct heat well.
• Jewelry: Gold and silver are used for ornaments.
• Transportation: Metals are used in vehicles and aircraft.

6. Uses of Non-Metals

• Oxygen: Essential for respiration.
• Nitrogen: Used in fertilizers.
• Chlorine: Used to purify water.
• Carbon: Used in fuels.
• Phosphorus: Used in matchsticks and fertilizers.

7. Chemical Properties of Metals

Reaction with Oxygen

Metals react with oxygen to form metal oxides.

Example:

Magnesium + Oxygen → Magnesium Oxide

Reaction with Water

Some metals react with water to produce hydrogen gas.

Reaction with Acids

Metals react with acids to produce salt and hydrogen gas.

Example:

Zinc + Hydrochloric Acid → Zinc Chloride + Hydrogen

8. Chemical Properties of Non-Metals

Reaction with Oxygen

Non-metals react with oxygen to form non-metal oxides.

Example:

Carbon + Oxygen → Carbon Dioxide

Reaction with Metals

Non-metals react with metals to form compounds.

Example:

Sodium + Chlorine → Sodium Chloride

9. Displacement Reactions

A displacement reaction occurs when a more reactive metal replaces a less reactive metal from its compound.

Example:

Iron + Copper Sulphate → Iron Sulphate + Copper

10. Corrosion

Corrosion is the gradual destruction of metals due to reactions with air, water, or chemicals.

A common example is rusting of iron.

Prevention of Corrosion

• Painting
• Oiling or greasing
• Galvanization
• Electroplating