class 10 chapter 3 science

                                                        SCORE CBSE
 

Chapter 3: Metals and Non-Metals

1. Properties of Metals

• Physical Properties:

  • Malleability: Metals can be hammered into thin sheets without breaking (e.g., gold, aluminum).
  • Ductility: Metals can be drawn into wires (e.g., copper, aluminum).
  • Conductivity: Metals are good conductors of heat and electricity (e.g., copper, silver).
  • Lustre: Metals have a shiny appearance when polished (e.g., gold, silver).
  • Density: Most metals have high density (e.g., iron, lead).
  • Melting and Boiling Points: Metals have high melting and boiling points (e.g., iron, copper).

• Chemical Properties:

  • Reaction with Oxygen: Metals react with oxygen to form metal oxides.
    • Example: $2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$
  • Reaction with Water: Some metals react with water to form metal hydroxides and hydrogen gas.
    • Example: $2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2$
  • Reaction with Acids: Metals react with acids to produce hydrogen gas and salts.
    • Example: $\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2$

2. Properties of Non-Metals

• Physical Properties:

  • Non-malleability: Non-metals are generally brittle and break easily.
  • Non-ductility: Non-metals cannot be drawn into wires.
  • Non-conductivity: Non-metals are poor conductors of heat and electricity (except graphite).
  • Lack of Lustre: Non-metals have a dull appearance (e.g., sulfur, phosphorus).
  • Low Density: Non-metals usually have a lower density compared to metals.

• Chemical Properties:

  • Reaction with Oxygen: Non-metals react with oxygen to form non-metal oxides.
    • Example: $\text{C} + \text{O}_2 \rightarrow \text{CO}_2$
  • Reaction with Water: Non-metals do not react with water in most cases.
  • Reaction with Acids: Non-metals do not react with acids to produce hydrogen gas.

3. Differences between Metals and Non-Metals

Property	Metals	Non-Metals
Physical State	Solid (except mercury, which is liquid)	Solid, liquid, or gas
Appearance	Shiny (lustrous)	Dull (except graphite)
Malleability	Malleable (can be hammered)	Non-malleable (brittle)
Ductility	Ductile (can be drawn into wires)	Non-ductile
Conductivity	Good conductors of heat and electricity	Poor conductors (except graphite)
Density	High density	Low density

4. Chemical Reactions of Metals and Non-Metals

• Reaction with Oxygen:

  • Metals react with oxygen to form metal oxides (basic in nature).
    • Example: $4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3$
  • Non-metals react with oxygen to form non-metal oxides (acidic in nature).
    • Example: $\text{S} + \text{O}_2 \rightarrow \text{SO}_2$

• Reaction with Water:

  • Some metals like sodium and potassium react vigorously with water, forming hydroxides and releasing hydrogen gas.
    • Example: $2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2$
  • Most non-metals do not react with water.

• Reaction with Acids:

  • Metals react with acids to release hydrogen gas and form salts.
    • Example: $\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2$
  • Non-metals generally do not react with acids to release hydrogen gas.

5. Uses of Metals and Non-Metals

• Uses of Metals:
  • Iron: Used to make steel, bridges, and buildings.
  • Aluminum: Used in the manufacture of aircraft, cooking utensils.
  • Copper: Used in electrical wiring due to its good conductivity.
  • Gold: Used in jewelry and as a standard for money.
• Uses of Non-Metals:
  • Oxygen: Essential for respiration and combustion.
  • Nitrogen: Used in fertilizers and in the production of ammonia.
  • Carbon: Used in the form of coal for energy and graphite in pencils.
  • Chlorine: Used for disinfecting drinking water and in making plastics.

6. Reactivity Series

• The Reactivity Series arranges metals in order of their reactivity.

  • Highly reactive metals: Potassium (K), Sodium (Na), Calcium (Ca), etc.

  • Moderately reactive metals: Magnesium (Mg), Aluminum (Al), Zinc (Zn), etc.

  • Less reactive metals: Copper (Cu), Silver (Ag), Gold (Au), etc.

  • Metals at the top of the series react more readily with water and acids, while metals at the bottom react less.

7. Corrosion

• Corrosion is the process where metals like iron are slowly destroyed by the action of air, moisture, and other chemicals.
  • Example: Rusting of iron.
    • Iron reacts with oxygen and water to form hydrated iron oxide (rust): $$4\text{Fe} + 3\text{O}_2 + 6\text{H}_2\text{O} \rightarrow 4\text{Fe(OH)}_3$$
  • Prevention of rusting includes painting, galvanization (coating with zinc), and using alloys.

8. Alloys

• Alloy is a mixture of two or more metals or a metal and a non-metal.
  • Example 1: Bronze (copper + tin) is used for making sculptures, coins.
  • Example 2: Brass (copper + zinc) is used in musical instruments, coins.

9. Practice Questions

1. What are the physical properties that distinguish metals from non-metals?
2. Write the chemical equation for the reaction of sodium with water.
3. Why is rusting considered a slow process of corrosion?
4. What is the significance of the reactivity series?

Conclusion

This chapter focuses on the various properties, reactions, and uses of metals and non-metals. Understanding the differences between them, their behavior in chemical reactions, and their applications is essential for grasping the concepts in chemistry.