Metals and Non-metals · Class 10 Science: 86 flashcards
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1. Define malleability with an example.
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The property of metals by which they can be beaten into thin sheets — e.g., gold and silver hammered into foils (silver vark, gold leaf); aluminium foil.
2. Define ductility with an example.
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The property of metals by which they can be drawn into thin wires — e.g., copper wires; 1 g of gold can be drawn into a ~2 km wire.
3. Which are the most malleable and ductile metals?
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Gold and silver — gold being the champion of both.
4. What does 'sonorous' mean? Give a use based on it.
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Producing a ringing sound when struck — the reason bells (and cymbals) are made of metals.
5. Name the best two conductors of electricity among metals.
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Silver (best) and copper (second — used for wiring because it is far cheaper).
6. Name two metals that are poor conductors relative to other metals.
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Lead and mercury.
7. Which metal is liquid at room temperature?
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Mercury (Hg) — used in thermometers.
8. Which non-metal is liquid at room temperature?
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Bromine.
9. Name two metals soft enough to be cut with a knife.
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Sodium and potassium (lithium as well).
10. Which two metals can melt on the palm of the hand?
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Gallium and caesium — their melting points are near body temperature.
11. Which non-metal is the hardest natural substance?
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Diamond — a form (allotrope) of carbon; it also has a very high melting point.
12. Which non-metal conducts electricity, and where is it used for this?
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Graphite (a form of carbon) — used as electrodes in dry cells and electrolysis.
13. Which non-metal has lustre?
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Iodine — a shiny, violet-black solid non-metal.
14. State four physical properties in which metals and non-metals differ.
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(1) Lustre: metals shiny, non-metals dull. (2) Malleability/ductility: metals yes, solid non-metals brittle. (3) Conduction: metals conduct heat/electricity, non-metals insulate. (4) Sonority: metals ring, non-metals thud. (Also state and melting points.)
15. Why are cooking vessels made of metals like aluminium and copper?
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Metals are good conductors of heat — the flame's heat passes quickly and evenly to the food.
16. Why is the covering of electric wires made of rubber or plastic?
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They are insulators (non-conductors of electricity), protecting users from shock while the metal core carries the current.
17. Why can't physical properties alone classify an element as metal or non-metal?
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The exceptions break every physical rule — sodium is soft, mercury liquid, graphite conducts, iodine shines. Reliable classification needs chemical properties, especially the nature of the element's oxide.
18. Which element has the highest melting point of all, and what is it used for?
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Tungsten (~3422 °C) — used as the filament of incandescent bulbs.
19. Give two uses each of malleability and ductility.
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Malleability: aluminium foil for packing; silver vark/gold leaf for decoration (also beaten body panels). Ductility: copper and aluminium electrical wires; gold wire in jewellery and electronics.
20. Why does a freshly cut piece of sodium lose its shine within seconds?
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Sodium is so reactive that its fresh surface immediately reacts with oxygen and moisture of air, forming a dull oxide layer — a preview of chemical properties.
21. What is generally formed when a metal burns in oxygen? Give an example.
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A metal oxide, generally basic in nature — e.g., 2Cu + O₂ → 2CuO (the black coating on heated copper).
22. Name two amphoteric oxides and define the term.
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Aluminium oxide (Al₂O₃) and zinc oxide (ZnO). Amphoteric oxides react with both acids and bases to give salt and water.
23. Write the reactions of aluminium oxide with (a) HCl, (b) NaOH.
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(a) Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O. (b) Al₂O₃ + 2NaOH → 2NaAlO₂ (sodium aluminate) + H₂O.
24. Why are sodium and potassium stored under kerosene?
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They react violently with air's oxygen and moisture — even catching fire if left in the open. Kerosene keeps air and water away.
25. Which metals react with COLD water? Write sodium's equation.
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Potassium and sodium react violently; calcium reacts less violently. 2Na + 2H₂O → 2NaOH + H₂↑ + heat.
26. Why does calcium float when reacting with water?
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The hydrogen gas produced sticks to its surface as bubbles, making the metal buoyant while it fizzes.
27. Which metal reacts with hot water but not cold? Write the equation.
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Magnesium: Mg + 2H₂O → Mg(OH)₂ + H₂↑ — it too floats on the hydrogen bubbles.
28. Which metals react only with steam? Write iron's steam reaction.
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Aluminium, zinc and iron. 3Fe + 4H₂O(g) → Fe₃O₄ + 4H₂.
29. Name four metals that never react with water in any form.
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Lead, copper, silver and gold.
30. Write the general reaction of a metal with a dilute acid, with the vigour order for Mg, Al, Zn, Fe.
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Metal + dilute acid → salt + hydrogen gas. Vigour decreases: Mg > Al > Zn > Fe.
31. Why doesn't copper react with dilute hydrochloric acid?
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Copper lies BELOW hydrogen in the reactivity series — it cannot displace hydrogen from acids.
32. Why is hydrogen gas usually NOT evolved when a metal reacts with nitric acid?
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HNO₃ is a strong oxidising agent — it oxidises the hydrogen produced straight to water, itself being reduced to nitrogen oxides. (Exception: very dilute HNO₃ with Mg or Mn gives H₂.)
33. What is aqua regia? What can it dissolve?
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A freshly prepared 3:1 mixture of concentrated HCl and concentrated HNO₃ — a fuming liquid that dissolves even gold and platinum.
34. What is a displacement reaction? Give an example with the series logic.
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Put a more reactive metal into the salt solution of a less reactive one and it pushes that metal out — e.g., Zn + CuSO₄ → ZnSO₄ + Cu because zinc stands above copper in the reactivity series.
35. Write the reactivity series from potassium to gold.
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K > Na > Ca > Mg > Al > Zn > Fe > Pb > (H) > Cu > Hg > Ag > Au.
36. How was the reactivity series established experimentally?
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Through pairwise displacement experiments — each metal tested in other metals' salt solutions; a metal displacing another ranks above it, and compiling all results gives the series.
37. Why does aluminium resist corrosion despite being a reactive metal?
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It instantly forms a thin, tough layer of aluminium oxide in air, which seals the surface and prevents any further attack.
38. What is anodising and how is it done?
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The process of thickening aluminium's protective oxide layer: the aluminium article is made the ANODE in electrolysis with dilute sulphuric acid; oxygen released at the anode builds up the oxide coat (which can be dyed).
39. Predict: copper strip in silver nitrate solution.
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Reaction occurs — copper is above silver: Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag; the solution turns bluish and grey silver deposits on the strip.
40. Predict: silver strip in copper sulphate solution.
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No reaction — silver is BELOW copper in the series and cannot displace it.
41. What happens when magnesium ribbon burns in air, and what is the product's nature?
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It burns with a dazzling white flame forming white magnesium oxide — a basic oxide (its solution turns red litmus blue).
42. Arrange in decreasing reactivity: Fe, Mg, Cu, Zn, Na.
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Na > Mg > Zn > Fe > Cu.
43. Why do atoms of elements react with one another?
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To achieve the stable, completely filled outermost shell (octet) of the nearest noble gas — by losing, gaining or sharing electrons.
44. What is a cation? How does a metal become one?
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A positively charged ion — a metal atom becomes a cation by LOSING its few outer electrons, e.g., Na → Na⁺ + e⁻.
45. What is an anion? How does a non-metal become one?
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A negatively charged ion — a non-metal atom gains the electrons it lacks, e.g., Cl + e⁻ → Cl⁻.
46. Define an ionic (electrovalent) bond.
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The strong electrostatic force of attraction between oppositely charged ions, formed when electrons transfer from a metal to a non-metal.
47. Show the electron transfer in the formation of NaCl.
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Na (2,8,1) loses its single outer electron → Na⁺ (2,8). Cl (2,8,7) gains that electron → Cl⁻ (2,8,8). The Na⁺ and Cl⁻ attract, forming the ionic bond.
48. Show the formation of MgO by electron transfer.
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Mg (2,8,2) loses two electrons → Mg²⁺ (2,8); O (2,6) gains both → O²⁻ (2,8). The doubly charged ions attract strongly: MgO.
49. Why does one magnesium need TWO chlorine atoms in MgCl₂?
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Magnesium must lose two electrons to complete its octet, but each chlorine can accept only one — so two chlorines are needed: Mg²⁺ + 2Cl⁻.
50. Do ionic compounds exist as molecules? Explain.
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No — they form giant three-dimensional crystal lattices of alternating cations and anions. The formula (like NaCl) only shows the RATIO of ions, not a molecule.
51. List the four characteristic properties of ionic compounds.
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(1) Hard, brittle, crystalline solids; (2) high melting and boiling points; (3) generally soluble in water, insoluble in kerosene/petrol; (4) conduct electricity in molten or dissolved state but not as solids.
52. Why do ionic compounds have high melting points?
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Melting requires breaking the strong electrostatic attractions between countless oppositely charged ions throughout the lattice — which needs a large amount of heat energy (NaCl melts at 1074 K).
53. Why doesn't solid NaCl conduct electricity?
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Its ions are locked in fixed positions in the rigid lattice — with no mobile charges, no current can flow.
54. Why does molten (or dissolved) NaCl conduct electricity?
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Melting or dissolving frees the ions from the lattice; the mobile Na⁺ and Cl⁻ ions then move toward the electrodes, carrying the current.
55. Why are ionic crystals brittle despite being hard?
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A blow shifts one layer of ions slightly, bringing like charges face-to-face; their strong repulsion splits the crystal along that plane.
56. In which solvents do ionic compounds dissolve, and in which not?
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Generally soluble in water (whose charged ends pull the ions apart); insoluble in solvents like kerosene and petrol which lack such charges.
57. Write the electronic configurations of Na, Na⁺, Cl and Cl⁻.
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Na: 2,8,1. Na⁺: 2,8. Cl: 2,8,7. Cl⁻: 2,8,8.
58. Derive the formula of the compound of calcium (2,8,8,2) with chlorine (2,8,7).
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Calcium loses 2 electrons; each chlorine accepts 1 — so Ca²⁺ + 2Cl⁻ → CaCl₂.
59. Derive the formula of the compound of sodium with oxygen (2,6).
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Each Na gives 1 electron but O needs 2 — so two sodiums per oxygen: 2Na⁺ + O²⁻ → Na₂O.
60. Why don't noble gases form ionic bonds?
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Their outermost shells are already complete — they have nothing to gain or lose energetically, so they are chemically inert.
61. Why is the chemistry of Na⁺ completely different from that of Na metal?
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Na⁺ has the stable noble-gas configuration (2,8) — it has no urge to react like the atom with its loose outer electron. An ion is a different chemical species from its parent atom.
62. What everyday observation shows the solubility rule of ionic compounds?
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Salt dissolves instantly in water (curry, dal) but stays undissolved in oil or kerosene — water's polarity dismantles the lattice; oils cannot.
63. Which industrial process depends on molten ionic compounds conducting electricity?
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Electrolytic extraction of reactive metals — e.g., sodium from molten NaCl and aluminium from molten Al₂O₃.
64. State the melting point of NaCl and what it demonstrates.
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About 1074 K (801 °C) — far above a kitchen flame — demonstrating the enormous strength of the ionic lattice's attractions.
65. Define mineral, ore and gangue.
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Minerals: naturally occurring compounds of metals in the earth's crust. Ore: a mineral from which metal can be extracted profitably. Gangue: the earthy impurities (sand, soil) mixed with the ore.
66. How are metals LOW in the reactivity series extracted? Give the mercury example.
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By heating alone (some are even found native). Cinnabar (HgS) heated in air: 2HgS + 3O₂ → 2HgO + 2SO₂; further heating: 2HgO → 2Hg + O₂.
67. How are metals in the MIDDLE of the series extracted?
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Their ores are first converted to oxides (roasting for sulphides, calcination for carbonates), then the oxides are reduced with carbon: e.g., ZnO + C → Zn + CO.
68. How are metals at the TOP of the series extracted? Why not with carbon?
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By electrolysis of their molten compounds (Na from molten NaCl, Al from molten Al₂O₃) — the metal deposits at the cathode. Carbon cannot reduce their oxides because these metals bind oxygen more strongly than carbon does.
69. Define roasting with an equation.
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Heating a sulphide ore strongly in EXCESS of air to convert it to the oxide: 2ZnS + 3O₂ → 2ZnO + 2SO₂.
70. Define calcination with an equation.
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Heating a carbonate ore strongly in LIMITED air to convert it to the oxide: ZnCO₃ → ZnO + CO₂.
71. Write the thermite reaction and its famous use.
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Fe₂O₃ + 2Al → Al₂O₃ + 2Fe + heat. The iron is produced molten and is used to weld railway tracks and broken machine parts.
72. Why does the thermite reaction produce MOLTEN iron?
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The reaction is enormously exothermic (~2500 °C) — the heat released melts the iron as it forms.
73. In electrolytic refining of copper, name the anode, cathode and electrolyte.
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Anode: a thick block of IMPURE copper. Cathode: a thin strip of PURE copper. Electrolyte: acidified copper sulphate solution.
74. What happens at each electrode during copper refining?
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At the anode, impure copper dissolves into the solution as Cu²⁺ ions; at the cathode, Cu²⁺ ions deposit as pure copper. The cathode grows while the anode shrinks.
75. What is anode mud and why is it valuable?
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The insoluble impurities that settle below the anode during refining — they often contain precious metals like silver and gold, which are recovered.
76. Define an alloy.
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A homogeneous mixture of a metal with one or more other metals (or with a non-metal), made by melting the components together.
77. How do an alloy's properties differ from the pure metal's?
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Alloys are generally harder, stronger and more corrosion-resistant, but have LOWER electrical conductivity and LOWER melting points than the pure metals.
78. Give the compositions of brass and bronze.
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Brass = copper + zinc. Bronze = copper + tin.
79. What is solder made of, and what property makes it useful?
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Lead + tin — its LOW melting point lets it melt easily to join electrical wires.
80. What is stainless steel and why doesn't it rust?
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Iron alloyed with chromium and nickel; the chromium forms an invisible protective oxide film, so the steel resists rusting — used for utensils and surgical instruments.
81. What is an amalgam?
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An alloy in which one of the metals is MERCURY — used, for example, in dental fillings.
82. Why is pure iron rarely used?
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It is too soft. Alloyed with a small amount of carbon (~0.05–2%) it becomes hard, strong steel — the practical form of iron.
83. Why is 22-carat gold used for ornaments instead of 24-carat?
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Pure (24-carat) gold is too soft for daily wear. 22-carat gold — 22 parts gold alloyed with 2 parts silver or copper — is hard enough for jewellery.
84. What is the sequence of steps in extracting a middle-zone metal from its sulphide ore?
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(1) Enrichment of the ore (remove gangue) → (2) roasting to the oxide → (3) reduction of the oxide with carbon → (4) refining (e.g., electrolytic) to pure metal.
85. Which alloy would you pick for: (a) a temple bell, (b) a rust-free knife, (c) joining circuit wires?
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(a) Bronze (sonorous, tough). (b) Stainless steel (Cr+Ni protection). (c) Solder (low melting point).
86. Why is sodium collected at the cathode in the electrolysis of molten NaCl?
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Na⁺ cations migrate to the negative electrode (cathode), where they gain electrons and are reduced to sodium metal; chlorine gas forms at the anode.
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