Metals and Non-metals – Revision Summary (NCERT Class 10)
1. Chapter at a Glance
- Elements are classified as metals or non-metals on the basis of physical and chemical properties.
- Metals are lustrous, malleable, ductile, sonorous and good conductors of heat and electricity; they form basic oxides and lie above hydrogen in the reactivity series.
- Non-metals are generally brittle, non-lustrous (except iodine), poor conductors (except graphite) and form acidic or neutral oxides.
- Metals react with oxygen, water and dilute acids at different rates; more reactive metals displace less reactive metals from their salt solutions.
- Ionic (electrovalent) compounds are formed by transfer of electrons from metals to non-metals and show high melting/boiling points, solubility in water and electrical conductivity in molten or aqueous state.
- Metals are extracted from ores by methods depending on their position in the reactivity series (reduction by heat, carbon or electrolysis).
- Corrosion of metals (rusting of iron, tarnishing of silver/copper) is prevented by painting, galvanisation, alloying, etc.
- Alloys are homogeneous mixtures of metals (or metal + non-metal) that improve properties such as hardness and corrosion resistance.
2. Definitions and Laws (exact NCERT wording)
- Metallic lustre: “Metals, in their pure state, have a shining surface. This property is called metallic lustre.”
- Malleability: “You will find that some metals can be beaten into thin sheets. This property is called malleability.”
- Ductility: “The ability of metals to be drawn into thin wires is called ductility.”
- Sonorous: “The metals that produce a sound on striking a hard surface are said to be sonorous.”
- Amphoteric oxides: “Such metal oxides which react with both acids as well as bases to produce salts and water are known as amphoteric oxides.”
- Ionic compounds / electrovalent compounds: “The compounds formed in this manner by the transfer of electrons from a metal to a non-metal are known as ionic compounds or electrovalent compounds.”
- Mineral: “The elements or compounds, which occur naturally in the earth’s crust, are known as minerals.”
- Ore: “At some places, minerals contain a very high percentage of a particular metal and the metal can be profitably extracted from it. These minerals are called ores.”
- Gangue: “Ores mined from the earth are usually contaminated with large amounts of impurities such as soil, sand, etc., called gangue.”
- Roasting: “The sulphide ores are converted into oxides by heating strongly in the presence of excess air. This process is known as roasting.”
- Calcination: “The carbonate ores are changed into oxides by heating strongly in limited air. This process is known as calcination.”
- Alloy: “An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal.”
- Galvanisation: “Galvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer of zinc.”
- Reactivity (activity) series: List of metals arranged in order of decreasing reactivity (K > Na > Ca > Mg > Al > Zn > Fe > Pb > [H] > Cu > Hg > Ag > Au).
- General reaction equations (NCERT):
- Metal + Oxygen → Metal oxide
- Metal + Water → Metal oxide + Hydrogen
- Metal oxide + Water → Metal hydroxide
- Metal + Dilute acid → Salt + Hydrogen
- Metal A + Salt solution of B → Salt solution of A + Metal B
3. Important Diagrams and Activities
- Fig. 3.1 (metal wire with wax and pin): Demonstrates that metals are good conductors of heat.
- Fig. 3.2 (electric circuit with metal sample): Shows metals conduct electricity.
- Fig. 3.3 (steam on metal): Action of steam on metals (Al, Fe, Zn).
- Fig. 3.4 (copper wire in FeSO₄ and iron nail in CuSO₄): Displacement reaction between metals.
- Fig. 3.5 & 3.6 (electron-dot structures): Formation of NaCl and MgCl₂ by electron transfer.
- Fig. 3.7 & 3.8 (heating salt & conductivity test): Properties of ionic compounds (high MP, conductivity in solution).
- Fig. 3.9 (activity series and metallurgy): Extraction methods for low/medium/high reactivity metals.
- Fig. 3.10 (steps in extraction of metals from ores): Summary flow-chart of metallurgy.
- Fig. 3.11 (thermit reaction): Joining railway tracks (highly exothermic displacement).
- Fig. 3.12 (electrolytic refining of copper): Refining of impure metals.
- Fig. 3.13 (rusting test tubes A, B, C): Conditions necessary for rusting of iron (air + water).
- Activities 3.1–3.7: Physical properties (lustre, malleability, ductility, hardness, conductivity, sonority) of metals vs non-metals.
- Activities 3.8–3.12: Chemical reactions with air, water, acids and salt solutions; reactivity order.
4. Common Misconceptions and Exam Pitfalls
- Assuming all metals are solids at room temperature (exceptions: Hg, Ga, Cs).
- Believing all non-metals are non-lustrous or non-conductors (iodine is lustrous; graphite conducts electricity).
- Confusing amphoteric oxides (Al₂O₃, ZnO) with only basic oxides.
- Forgetting that HNO₃ does not evolve H₂ with most metals (strong oxidising agent) except very dilute HNO₃ with Mg/Mn.
- Writing “rust” instead of specifying conditions (both air and moisture required).
- Missing that ionic compounds conduct electricity only in molten/aqueous state, not in solid state.
- Reversing reactivity order or forgetting that metals above H displace H₂ from acids.
- Using “ore” and “mineral” interchangeably in definitions.
5. Formula Sheet
No numerical formulas or SI units are given in the chapter. All equations are word or balanced chemical equations listed under “Definitions and Laws”.