Metals and Non-Metals

Introduction to Metals and Non-Metals

Metals and non-metals are two categories of elements that differ in their physical and chemical properties. These elements are fundamental to understanding chemistry and play crucial roles in our everyday lives. Metals like iron, aluminum, and copper are used in construction, electronics, and machinery, while non-metals like oxygen and sulfur are essential in biological processes and chemical manufacturing.

Physical Properties of Metals and Non-Metals

Metals

• Malleability: Metals can be hammered into thin sheets. Gold and silver are the most malleable metals. This property makes metals useful in industries like jewelry making and metal sheet production.
• Ductility: Metals can be drawn into thin wires. Copper and aluminum are examples of highly ductile metals used in electrical wiring.
• Luster: Metals, in their pure form, have a shiny appearance. This property is called metallic luster.
• Hardness: Most metals are hard, but their hardness varies. Sodium and potassium are soft metals that can be cut with a knife, while iron and titanium are much harder.
• Conductivity: Metals are excellent conductors of heat and electricity. Silver and copper are the best conductors, which is why they are used in electrical circuits.

Non-Metals

• Non-lustrous: Non-metals, such as sulfur and phosphorus, do not have a shiny appearance except for graphite and iodine, which have a luster.
• Non-malleable and Non-ductile: Non-metals are brittle, and they break into pieces when hammered or stretched. They cannot be shaped into sheets or wires.
• Poor Conductors: Non-metals are poor conductors of heat and electricity, except for graphite, which conducts electricity due to its free electrons.
• Physical States: Most non-metals exist as gases at room temperature (e.g., oxygen and nitrogen), while some, like sulfur and phosphorus, are solids. Bromine is a liquid non-metal.

Chemical Properties of Metals and Non-Metals

Metals

• Reaction with Oxygen: Metals react with oxygen to form metal oxides, which are generally basic in nature. Some metals like sodium and potassium react vigorously with oxygen, while others like gold and platinum do not react easily.
  
• Reaction with Water: Metals like sodium and potassium react violently with water to form metal hydroxides and hydrogen gas.
  
  Metals like aluminum and iron react with steam, while metals like copper, silver, and gold do not react with water.
• Reaction with Acids: Metals react with dilute acids to produce salt and hydrogen gas.
  ​
  However, metals like copper, silver, and gold do not react with dilute acids.

Non-Metals

• Reaction with Oxygen: Non-metals react with oxygen to form non-metallic oxides, which are acidic in nature.
  ​
  Carbon reacts with oxygen to form carbon dioxide, a common non-metallic oxide.
• Reaction with Water: Non-metals generally do not react with water.
• Reaction with Acids: Non-metals do not usually react with acids, as they do not displace hydrogen from acids like metals do.

Reactivity Series of Metals

The Reactivity Series is a list of metals arranged in decreasing order of their reactivity. It helps in predicting how metals will react with water, acids, and oxygen. The most reactive metals like potassium and sodium are placed at the top, while less reactive metals like silver and gold are at the bottom.

Occurrence of Metals and Non-Metals

Metals

• Metals are generally found in the Earth’s crust in the form of ores, from which they are extracted through various methods. For example, iron is extracted from its ore haematite, while aluminum is extracted from bauxite.

Non-Metals

• Non-metals like oxygen, nitrogen, and hydrogen are found in the atmosphere, while others like sulfur and carbon are found in the Earth’s crust.

Alloys and Corrosion

Alloys

Alloys are mixtures of metals with other metals or non-metals to improve their properties.

• Steel is an alloy of iron and carbon.
• Brass is an alloy of copper and zinc.
  Alloys have enhanced properties such as increased strength, resistance to corrosion, or better electrical conductivity.

Corrosion

Corrosion is the gradual degradation of metals due to their reaction with moisture, air, or chemicals in their environment. The most common example of corrosion is rusting, where iron reacts with oxygen and moisture to form iron oxide.

Methods to prevent corrosion:

• Galvanization: Coating iron with a layer of zinc.
• Painting or Oiling: Covering metal surfaces to prevent exposure to air and moisture.

Ionic Compounds

When a metal reacts with a non-metal, an ionic compound is formed. These compounds consist of positive and negative ions held together by strong electrostatic forces. For example, when sodium reacts with chlorine, it forms sodium chloride ():

Properties of Ionic Compounds:

• High melting and boiling points.
• Conduct electricity when dissolved in water or in molten form.
• Soluble in water but generally insoluble in organic solvents like kerosene or petrol.

Real-life Applications of Metals and Non-Metals

Metals:

• Copper is used in electrical wiring due to its excellent conductivity.
• Aluminum is used in making aircraft bodies due to its lightweight and high strength.

Non-Metals:

• Oxygen is essential for respiration in living organisms and combustion processes.
• Nitrogen is used in fertilizers to enhance plant growth.

Practice Questions with Answers

Q1. What happens when magnesium reacts with hydrochloric acid? Write the equation.

• Answer: Magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas.
  • Equation:

Q2. Why is copper used for electrical wiring instead of steel?

• Answer: Copper is a better conductor of electricity compared to steel and is more malleable and ductile.

Q3. What is an alloy? Give two examples.

• Answer: An alloy is a mixture of two or more metals or a metal and a non-metal. Examples include brass (copper + zinc) and steel (iron + carbon).

FAQs