Grade 9–10, CBSE/ICSE/Australian Curriculum

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Physical and Chemical Properties of Metals and Non-Metals

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1. Physical Properties

Metals

1. Lustre (Shiny appearance):

   • Metals are generally lustrous (shiny) in nature.

   • Example: Gold, silver, copper.

   • Exceptions: Sodium and potassium are dull but can be shiny when freshly cut.

2. Hardness:

   • Most metals are hard.

   • Exceptions: Sodium and potassium are soft (can be cut with a knife).

3. Malleability (ability to be hammered into thin sheets):

   • Metals are malleable.

   • Example: Aluminium foil, gold foil.

4. Ductility (ability to be drawn into wires):

   • Metals are ductile.

   • Example: Copper and aluminium wires.

   • Gold is the most ductile metal.

5. Conductivity:

   • Good conductors of heat and electricity.

   • Silver and copper are the best conductors.

   • Lead and mercury are poor conductors (exceptions).

6. Melting and Boiling Point:

   • Generally high.

   • Example: Tungsten has the highest melting point.

   • Exceptions: Sodium, potassium, and mercury have low melting points.

7. Density:

   • Metals are generally dense.

   • Exceptions: Sodium and potassium are light metals (low density).

8. Sonority:

   • Metals produce a ringing sound when struck (sonorous).

   • Example: Bells made of bronze.

Non-Metals

1. Lustre:

   • Generally non-lustrous (dull).

   • Exceptions: Iodine is lustrous.

2. Hardness:

   • Non-metals are usually soft.

   • Exception: Diamond (a form of carbon) is the hardest natural substance.

3. Malleability and Ductility:

   • Non-metals are brittle (break easily when hammered).

   • They are neither malleable nor ductile.

4. Conductivity:

   • Non-metals are poor conductors of heat and electricity (insulators).

   • Exceptions: Graphite (a form of carbon) is a good conductor of electricity.

5. Melting and Boiling Point:

   • Usually low compared to metals.

   • Exceptions: Diamond has a very high melting point.

6. Density:

   • Usually have low density.

7. State:

   • Exist in all three states:

     • Solid: Sulphur, phosphorus.

     • Liquid: Bromine.

     • Gas: Oxygen, nitrogen, chlorine.

2. Chemical Properties

Metals

1. Reaction with Oxygen:

   • Metals form metal oxides (usually basic in nature).

   • Example:

     • 4Na + O₂ → 2Na₂O (sodium oxide, strongly basic)

     • 2Mg + O₂ → 2MgO (magnesium oxide, weakly basic)

   • Some oxides are amphoteric (show both acidic and basic properties), e.g., Al₂O₃, ZnO.

2. Reaction with Water:

   • Highly reactive metals (Na, K, Ca) react vigorously with water to form hydroxides and release hydrogen gas.

     • 2Na + 2H₂O → 2NaOH + H₂↑

   • Less reactive metals (Mg, Fe) react slowly with water.

   • Very less reactive metals (Cu, Ag, Au) do not react with water.

3. Reaction with Acids:

   • Metals react with dilute acids (like HCl, H₂SO₄) to form a salt and hydrogen gas.

     • Zn + 2HCl → ZnCl₂ + H₂↑

   • Exceptions: Copper, silver, and gold do not react with dilute acids.

4. Reaction with Bases:

   • Some metals (like Zn, Al) react with strong bases (NaOH, KOH) to form complex salts.

     • Zn + 2NaOH → Na₂[ZnO₂] + H₂↑

5. Displacement Reactions:

   • A more reactive metal displaces a less reactive metal from its salt solution.

     • Fe + CuSO₄ → FeSO₄ + Cu

Non-Metals

1. Reaction with Oxygen:

   • Non-metals form non-metallic oxides, which are generally acidic in nature.

   • Example:

     • C + O₂ → CO₂ (carbon dioxide, acidic oxide)

     • S + O₂ → SO₂ (sulphur dioxide, acidic oxide)

2. Reaction with Water:

   • Non-metals generally do not react with water.

   • Exception: Chlorine dissolves in water to form an acidic solution (HCl + HOCl).

3. Reaction with Acids:

   • Non-metals generally do not react with acids.

4. Reaction with Bases:

   • Non-metals may react with strong bases to form salts.

   • Example: Cl₂ + 2NaOH → NaCl + NaOCl + H₂O

5. Displacement Reactions:

   • A more reactive non-metal can displace a less reactive non-metal from its salt solution.

   • Example: Cl₂ + 2KBr → 2KCl + Br₂

Comparison Table

Property	Metals	Non-Metals
Lustre	Shiny	Dull (except iodine)
Hardness	Generally hard	Generally soft (except diamond)
Malleability/Ductility	Malleable, ductile	Brittle
Conductivity	Good conductors	Poor conductors (except graphite)
Oxides	Basic/Amphoteric	Acidic
Reaction with Acids	Produces H₂ gas	Generally no reaction
State	Mostly solid (except mercury)	Solid, liquid, gas

✨ In short:

• Metals: Shiny, hard, malleable, ductile, conductors, form basic oxides, react with acids.

• Non-Metals: Dull, brittle, insulators, form acidic oxides, do not react with acids.