Class 10 Science - Chapter 3: Metals and Non-Metals

Overview

• This chapter explores the concepts of metals and non-metals.
• Focus on physical and chemical properties with NCERT visuals and animations.

Division of Elements

• Elements in our surroundings are divided into two main parts:
  • Metals
  • Non-metals

Physical Properties of Metals

Key Characteristics

1. Opacity and Luster

   • Metals are generally opaque and have a shiny surface (luster).
   • Example: Gold, Silver, Copper, Iron

2. Hardness

   • Most metals are hard (e.g., Iron, Copper, Silver).
   • Exceptions: Alkali metals (e.g., Sodium, Potassium) are soft and can be cut with a knife.

3. Strength

   • Metals have high tensile strength, which is the ability to resist deformation under tension.
   • Example: Used in buildings and bridges (e.g., Iron, Copper).
   • Exception: Sodium and Potassium are soft metals.

4. State

   • Metals are typically solid at room temperature; the exception is Mercury, which is liquid.

5. Sound

   • Metals produce sound when struck, making them sonorous.

6. Conduction

   • Metals are good conductors of heat and electricity.
   • Example: Electric wires and kitchen utensils are made of metals.

7. Malleability

   • Metals can be beaten into thin sheets (e.g., Iron).

8. Ductility

   • Metals can be drawn into wires.

9. Melting and Boiling Point

   • Metals generally have high melting and boiling points but exceptions exist (e.g., Sodium, Potassium have lower values).

10. Density

    • Metals typically have high density, with some exceptions.

11. Color

    • Generally, metals have a grey color, with exceptions like Gold and Copper.

Physical Properties of Non-Metals

Key Characteristics

1. Hardness

   • Non-metals are generally soft, with an exception being Diamond, which is very hard.

2. State

   • Non-metals exist in all three states (Solid: e.g. Wood; Liquid: e.g. Bromine; Gas: e.g. Oxygen).

3. Luster

   • Non-metals typically have a dull appearance, with exceptions like Diamond and Iodine.

4. Sonority

   • Non-metals are not sonorous, with the exception of Graphite.

5. Malleability & Ductility

   • Non-metals are neither malleable nor ductile; they are brittle.

6. Melting and Boiling Point

   • Most non-metals have lower melting and boiling points, except for Diamond and Graphite.

7. Density

   • Non-metals usually have low density.

One-Word Questions

1. Which metal is liquid at room temperature?
   • Answer: Mercury
2. Which metal is the poorest conductor of heat?
   • Answer: Lead
3. Which metal can be cut with a knife?
   • Answer: Sodium
4. Which metal is the best conductor of electricity?
   • Answer: Silver

Chemical Properties of Metals

1. Reaction with Air (Oxygen)

• Metals react with oxygen to form metal oxides:
  • E.g. Copper + Oxygen → Copper Oxide
• Most metal oxides are basic in nature.
• Some metals react vigorously, while others have protective oxide layers.

2. Reaction with Water

• Metals react with water to form metal oxides or hydroxides and release hydrogen gas:
  • E.g. Sodium + Water → Sodium Hydroxide + Hydrogen
• Reactivity varies: Sodium and Potassium reaction occurs even with cold water.

3. Reaction with Acids

• Metals react with dilute acids to form salts and release hydrogen gas:
  • Example: Metal + Acid → Salt + H₂

4. Displacement Reaction

• A more reactive metal can displace a less reactive metal from its salt solution:
  • E.g. Fe + CuSO₄ → FeSO₄ + Cu

Reactivity Series

• Arranged metals in descending order of reactivity to predict displacement reactions.

Reactivity of Non-Metals with Metals

• Non-metals can react with metals forming ionic compounds (e.g. Sodium Chloride).

Occurrence of Metals

Terms to Understand

• Minerals: Naturally occurring compounds in the Earth’s crust.
• Ores: Minerals that contain a high percentage of a specific metal.

Extraction of Metals from Ores

Steps

1. Enrichment of Ores: Removal of impurities (gang) from ores.

   • Methods: Hydraulic washing, Magnetic separation, Froth flotation, Chemical separation.

2. Extraction of Metal: Reduction of ore to extract metal based on its reactivity.

   • Low reactivity: Roasting or calcination.
   • High reactivity: Electrolytic reduction.

Electrolytic Refining Process

• Method to obtain pure metal; involves passing electric current through a solution of metal salt.

Prevention of Corrosion

• Methods:
  1. Painting – Protects from moisture.
  2. Greasing – Keeps moisture away.
  3. Galvanization – Coating with zinc to prevent corrosion.
  4. Making Alloys – Non-corrosive mixtures (e.g. Bronze, Brass).

Conclusion

• Summary of key points and properties of metals and non-metals along with their reactions.
• Encouragement to subscribe to the channel for updates on future content.

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Additional Notes

• Ensure to explore practical applications and safety measures while dealing with metals and their reactions.
• Good comprehension of this chapter is vital for understanding further concepts in chemistry.