Chapter: Metals and Non-Metals CBSE 10th Science

Metals and Non-Metals

Metals and Non-Metals

Metals and Non-Metals

Metals:

  • They are good conductors of heat and electricity.
  • They have a shiny or metallic luster.
  • They are generally solid at room temperature (except for mercury).
  • They are malleable, which means they can be hammered into different shapes.
  • They are ductile, which means they can be drawn into wires.

Non-Metals:

  • They are generally poor conductors of heat and electricity.
  • They lack the shiny luster that metals have.
  • They can be in different states at room temperature (e.g., hydrogen and oxygen are gases, sulfur is a solid, and nitrogen is a gas).
  • They are typically brittle and cannot be hammered into thin sheets or drawn into wires.

Properties of Metals:

  1. Good Conductors: Metals are excellent conductors of heat and electricity.
  2. Luster: They have a shiny, metallic luster.
  3. Malleability: Metals can be hammered into thin sheets without breaking.
  4. Ductility: They can be drawn into thin wires.
  5. Solid State: Most metals are solid at room temperature (except mercury).
  6. High Melting and Boiling Points: Metals generally have high melting and boiling points.
  7. Sonorous: They produce a ringing sound when struck.
  8. Tendency to Lose Electrons: Metals tend to lose electrons and form positively charged ions (cations) in chemical reactions.

Properties of Non-Metals:

  1. Poor Conductors: Non-metals are poor conductors of heat and electricity.
  2. Dull Appearance: They lack the shiny luster of metals and may appear dull.
  3. Various States: Non-metals can exist in different states at room temperature (e.g., hydrogen and oxygen are gases, sulfur is a solid, and nitrogen is a gas).
  4. Brittle: They are typically brittle and cannot be drawn into thin wires or hammered into sheets.
  5. Low Melting and Boiling Points: Non-metals generally have low melting and boiling points.
  6. Not Sonorous: They do not produce a ringing sound when struck.
  7. Tendency to Gain Electrons: Non-metals tend to gain electrons and form negatively charged ions (anions) in chemical reactions.

1. Reaction with Oxygen:

  • Most metals react with oxygen to form metal oxides. This process is known as oxidation.
  • Example: 2Hg(l) + O2(g) → 2HgO(s) (Formation of mercury oxide)

Amphoteric Oxides:

Amphoteric oxides are certain chemical compounds that exhibit dual properties, acting as both acids and bases in different reactions.

Example (Acidic Reaction):
  • Aluminum oxide (Al2O3) reacts with hydrochloric acid (HCl) to form aluminum chloride (AlCl3) and water (H2O):
  • Al2O3 + 6HCl → 2AlCl3 + 3H2O
Example (Basic Reaction):
  • Zinc oxide (ZnO) reacts with sodium hydroxide (NaOH) to produce sodium zincate (Na2ZnO2) and water (H2O):
  • ZnO + 2NaOH → Na2ZnO2 + H2O

2. Reaction with Water:

  • Some metals react with water to produce metal hydroxides and hydrogen gas.
  • Example: 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) (Formation of sodium hydroxide and hydrogen gas)

Non-Metals:

Non-metals, when reacting with water, generally do not produce hydroxides or hydrogen gas. Instead, they might produce acidic solutions or remain inert.

3. Reaction with Acids:

  • Many metals react with acids to produce metal salts and hydrogen gas.
  • Example: Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) (Formation of zinc chloride and hydrogen gas)

Non-Metals:

Non-metals typically do not react with acids, though some may react with bases to form salts.

4. Reaction with Bases:

  • Some metals react with bases to produce metal hydroxides and hydrogen gas.
  • Example: Zn(s) + 2NaOH(aq) → Na2ZnO2(aq) + H2(g) (Formation of sodium zincate and hydrogen gas)

Non-Metals:

Non-metals generally do not react with bases, although some may react with acids to form salts.

5. Corrosion:

  • Corrosion is the gradual destruction of metals due to chemical reactions with their environment.
  • Example: Rusting of iron (Fe) in the presence of oxygen and moisture: 4Fe(s) + 3O2(g) + 6H2O(l) → 4Fe(OH)3(s) (Formation of rust)

Prevention of Corrosion:

  • Painting: Applying a coat of paint to prevent exposure to air and moisture.
  • Galvanization: Coating iron with a layer of zinc.
  • Oil or Grease Coating: Applying oil or grease to prevent contact with moisture.

6. Uses of Metals and Non-Metals:

  • Metals: Used in construction, manufacturing, electrical wiring, and machinery.
  • Non-Metals: Used in fertilizers, pharmaceuticals, and as gases in industrial processes.

7. Noble Metals:

  • Gold, Silver, and Platinum: These metals are resistant to corrosion and oxidation.

Applications:

  • Jewelry: Gold and silver are used in jewelry making.
  • Industrial Uses: Platinum is used in catalytic converters.