Metals and Non-metals Class 10 Notes | YoLearn.ai

Key Points to Remember

• Reactivity Series: K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au. Higher metals displace lower metals from their salt solutions.
• Amphoteric Oxides: Metal oxides that react with both acids and bases to produce salt and water (e.g., Al₂O₃, ZnO).
• Ionic Bonds: Formed by the complete transfer of electrons from a metal (cation) to a non-metal (anion).
• Properties of Ionic Compounds: High melting/boiling points, soluble in water, conduct electricity in molten state or aqueous solution (due to free ions).
• Metallurgy: The process of extracting metals from their ores and refining them.
• Gangue: Impurities (e.g., sand, rocky material) present in an ore.
• Corrosion: The gradual deterioration of a metal due to its reaction with air, moisture, or chemicals in the environment.
• Alloys: Homogeneous mixtures of two or more metals, or a metal and a non-metal, to improve properties.
• Anodising: Process of forming a thick oxide layer on aluminium to make it resistant to corrosion.

Essential Definitions

Malleability

The property of metals to be beaten into thin sheets without breaking (e.g., gold, silver).

Ductility

The property of metals to be drawn into thin wires (e.g., gold, copper).

Sonorous

The property of producing a ringing sound when struck (characteristic of metals).

Ore

A rock or mineral from which a metal can be economically extracted.

Roasting

Heating a sulphide ore strongly in the presence of excess air to convert it into a metal oxide.

Calcination

Heating a carbonate ore strongly in a limited supply of air to convert it into a metal oxide.

Amalgam

An alloy where one of the constituent metals is mercury.

Galvanisation

A method of protecting steel and iron from rusting by coating them with a thin layer of zinc.

Thermite Reaction

A highly exothermic reaction where metals like iron oxide react with aluminium, often used for welding railroad tracks.

Physical Properties: Metals vs. Non-metals

Chemical Properties of Metals

Metals exhibit distinct chemical behaviours based on their electron configuration, typically having 1, 2, or 3 valence electrons which they tend to lose to form positive ions (cations).

1. Reaction with Oxygen (Air):

• Most metals react with oxygen to form metal oxides. These oxides are generally basic in nature, turning red litmus blue. For example, magnesium burns in air to form magnesium oxide: 2Mg(s) + O₂(g) → 2MgO(s).
• Some metal oxides, like aluminium oxide (Al₂O₃) and zinc oxide (ZnO), are amphoteric. This means they react with both acids and bases to produce salt and water.
• Al₂O₃(s) + 6HCl(aq) → 2AlCl₃(aq) + 3H₂O(l)
• Al₂O₃(s) + 2NaOH(aq) → 2NaAlO₂(aq) + H₂O(l) (Sodium aluminate)
• Different metals show varying reactivities. Sodium and potassium react vigorously even at room temperature, while iron reacts slowly upon heating. Gold and silver do not react with oxygen even at high temperatures.

1. Reaction with Water:

• Metals react with water to form metal oxides/hydroxides and hydrogen gas.
• Cold water: Highly reactive metals like Na, K, Ca react vigorously with cold water. 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g) + Heat.
• Hot water: Less reactive metals like Magnesium react with hot water. Mg(s) + 2H₂O(l) → Mg(OH)₂(aq) + H₂(g).
• Steam: Metals like Aluminium, Iron, Zinc react only with steam, forming metal oxides. 2Al(s) + 3H₂O(g) → Al₂O₃(s) + 3H₂(g).
• Lead, Copper, Silver, Gold do not react with water or steam.

1. Reaction with Acids (Dilute):

• Most metals react with dilute acids to form metal salt and hydrogen gas. Metal + Dilute Acid → Metal Salt + Hydrogen.
• Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)
• However, copper, silver, gold do not react with dilute acids to liberate hydrogen because they are less reactive than hydrogen (lie below H in the reactivity series).

1. Reaction with Salt Solutions (Displacement Reactions):

• A more reactive metal displaces a less reactive metal from its salt solution. This is governed by the Reactivity Series.
• Reactivity Series (Decreasing Order): K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au.
• Example: Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s) (Iron is more reactive than copper).
• A less reactive metal cannot displace a more reactive metal. Cu(s) + FeSO₄(aq) → No Reaction.

Extraction of Metals (Metallurgy)

1. 1. Enrichment of Ore (Concentration) — Removal of unwanted impurities (gangue) from the ore. Methods include hydraulic washing, magnetic separation, froth flotation, and leaching, depending on the ore's properties.
2. 2. Extraction of Metal from Concentrated Ore — This step varies based on the metal's reactivity:
3. 3. Refining of Metals — The extracted metal is often impure. Electrolytic refining is the most common method. The impure metal is made the anode, a thin strip of pure metal is the cathode, and a salt solution of the metal is the electrolyte. On passing current, pure metal deposits at the cathode, and impurities collect below the anode (anode mud).

Worked Examples

• {"title":"1. Formation of Sodium Chloride (NaCl)","description":"Sodium (Na) has 1 valence electron, Chlorine (Cl) has 7. Na transfers its 1 valence electron to Cl. Na becomes Na⁺ (stable octet), Cl becomes Cl⁻ (stable octet). These oppositely charged ions are held by strong electrostatic forces, forming an ionic bond in NaCl."}
• {"title":"2. Reaction of Zinc with Sulphuric Acid","description":"When zinc metal reacts with dilute sulphuric acid, zinc sulphate and hydrogen gas are produced. Zinc is more reactive than hydrogen and displaces it from the acid.\nZn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)"}
• {"title":"3. Rusting of Iron","description":"Iron reacts with oxygen and moisture (water) in the air to form hydrated iron(III) oxide, commonly known as rust.\n4Fe(s) + 3O₂(g) + xH₂O(l) → 2Fe₂O₃.xH₂O(s) (Rust)"}

Exam Tip: Common Traps & Marking Cues

1. Reactivity Series: Memorise the reactivity series accurately! Questions often test displacement reactions or why certain metals react differently with water/acids.
2. Balancing Chemical Equations: Always ensure chemical equations are balanced for all reactions (oxidation, reduction, displacement, formation).
3. Exceptions: Pay attention to exceptions in physical properties (e.g., mercury is liquid metal, iodine is lustrous non-metal, graphite conducts electricity).
4. Amphoteric Oxides: Be ready to provide examples and explain their dual nature.
5. Ionic vs. Covalent: Clearly distinguish between electron transfer (ionic) and electron sharing (covalent) and properties of their respective compounds.
6. Diagrams: Practice drawing simple diagrams for electrolytic refining.

Quick Revision Check

• Q: Name two metals that react vigorously with cold water. A: Sodium (Na) and Potassium (K).
• Q: What is gangue? How is it removed from the ore? A: Gangue refers to the unwanted impurities present in an ore. It is removed during the enrichment or concentration of the ore using various physical or chemical methods.
• Q: Why are ionic compounds generally hard and have high melting points? A: Ionic compounds have strong electrostatic forces of attraction between oppositely charged ions, forming a rigid crystal lattice. A significant amount of energy is required to break these strong forces, leading to high melting points and hardness.
• Q: How is aluminium protected from corrosion? A: Aluminium is protected by anodising, which is the process of forming a thick, protective oxide layer on its surface, preventing further corrosion.

Frequently Asked Questions