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Ncert class 10 - science - chapter 3 - metals and non-metals
- 1. Metals and Non- metals ClassX – Science Chapter 3 Chemistry
- 2. Metals vs Non-metals– Physical properties Metals Non-Metals Lose electrons to become positive ions Cations e.g. Na+, Mg 2+ Gain electrons to become negative ions Anions e.g. Cl- , O2- Solid at room temperature except Mercury May be solid (Carbon, Sulphur), liquid (Bromine) or gas (Chlorine, Oxygen) Lustrous (Shining) Non-lustrous except Iodine Strong except (Sodium Na or Potassium K) Brittle Hard except Na & K which can be cut with Knife Soft except diamond Malleable – drawn into sheets Non-malleable Ductile – draw into wires Non-ductile High melting and boiling point (except Na and K) Low Melting and Boiling point except diamond
- 3. Metals vs Non-metals– Physical properties Metals Non-Metals High densities (Heavy elements) Low densities (Light elements) Good conductor of electricity and heat. Lead is poor conductor of heat Poor conductor of electricity (except graphite) and heat Sonorous Non-sonorous Lies on the left hand side of the periodic table. Lies on the right hand of the periodic table.
- 4. • Activity toshow that Metals are lustrous Inference: Metal surfaces are lustrous in nature. Activity 3.1 – Lustrous property Take a dull metal strip such as Iron or Copper Rub the metal surface with sand paper Metal shows Shining surface
- 5. • Activity toshow that Metals are hard Inference: Metals are hard by nature except few metals such as Sodium, Magnesium and Potassium. Activity 3.2 – Hardness of metal Take different metals such as Iron, Copper, Aluminium, Magnesium and Sodium Only Magnesium and Sodium can be cut with knife.
- 6. • Activity toshow that Metals are malleable Inference: Metals can be beaten into thin sheets. This property is called Malleability. Activity 3.3 – Malleability of Metals Take metals such as Iron, Zinc, lead and Copper. Hammer them Metals change their shape and beaten into thin sheets
- 7. • Activity toshow that Metals are ductile Inference: Metals can be pulled into wires. This property is called Ductility. Activity 3.4 – Ductility of Metals Observe the materials common wires are made of One could note that wires are made of metals such as Copper, Iron, Aluminium and Lead
- 8. Activity 3.5 –Metals conduct heat • Activity to show that Metals are good conductors of heat Inference: Metals conduct heat which melts the wax at the other end. Fix a copper wire on the Clamp stand as shown in figure. Fix a pin on the free end of the wire using wax Heat the wire with burner at other end. After some time, pin drops.
- 9. Activity 3.6 –Metals conduct Electricity • Activity to show that Metals are good conductors of electricity Inference: Metals conduct electricity which is indicated by the Glowing Bulb. Setup an electric circuit as shown in the figure Place a metal between terminals A and B
- 10. Activity 3.7 –Physical properties of Non-Metals • Collect samples of Carbon, Sulphur and Iodine and note down the physical properties. Element Symbol Types of Surface Hardness Malleab ility Ductility Conduction Sonorit y Heat Electrici ty Carbon C Non- lustrous Hard --- --- No Graphit e – Yes -- Sulphur S Non- lustrous Soft --- --- No No -- Iodine I Jon- lustrous Soft --- --- No No ---
- 11. Metals vs Non-metals– Chemical Properties Metals Metal + Oxygen Metal oxide Metal + Water Metal oxides / Metal Hydroxides + Hydrogen Metal + Acid Metal Salt + Hydrogen Non-Metals Non-metal + Oxygen Non- metal Oxide Do not react with Water to evolve Hydrogen. They cannot give electron to Hydrogen in water Non-Metals do not react with acids to release the gas.
- 12. Metals vs Non-metals– Chemical Properties Metals Metal + Salt Solution More reactive metal will displace less reactive metal Metal + Chlorine Metal chloride Metal + Hydrogen Metal Hydride Non-Metals Non-Metal + Salt Solution More reactive non-metal will displace less reactive non- metal Non-Metal + Chlorine Non- Metal chloride (Covalent bond is formed) Non-Metal + Hydrogen Non-Metal Hydride
- 13. Metals with Oxygen •Almost all metals combine with oxygen to form metal oxides Metal + Oxygen Metal Oxide For example, when is heated in air, it combines with oxygen to form copper (II) oxide, a black oxide. 2Cu + O2 2CuO (Copper) (Oxygen) (Copper (II) oxide) Aluminium forms Aluminium Oxide. 4Al + 3O2 2Al2O3 (Aluminium) (Oxygen) (Aluminium oxide)
- 14. Nature of Metaloxides NatureofMetalOxides Basic in nature e.g. Copper Oxide Amphoteric i.e. reacts with both acids & base e.g. Aluminium Oxide, Zinc Oxide Al2O3 + 6 HCl 2 AlCl3 + 3 H2O Al2O3 + 2 NaOH 2 NaAlO3 + H2O (Sodium Aluminate)
- 15. Nature of Metaloxides NatureofMetalOxides Insoluble in water Only certain Metal oxides dissolve in water to form alkalis e.g. Sodium oxide and Potassium Oxide Na2O (s) + H2O (l) 2 NaOH (aq) K2O (s) + H2O (l) 2KOH (aq)
- 16. Activity 3.9 –Observation of Burning Metals • Burn metals with the help of pair of tongs to record the following observations: S.No. Metal Colour of Flame Colour of Burnt Metal Solubility in Water 1 Na Yellow White Soluble 2 Ca Brick Red colour White Partially Soluble 3 Mg White White Soluble in hot water 4 Al White flame White Insoluble 5 Zn No colour White Insoluble 6 Fe No colour Reddish Insoluble 7 Cu Greenish Blue Black Insoluble
- 17. Non-Metals with Oxygen •Non-metals react with oxygen to form non-metal oxide Non-Metal + Oxygen Non-Metal Oxide • Non-metal oxides are acidic. C (s) + O2 (g) CO2 (g) S (s) + O2 (g) SO2 (g) N2 (g) + 2O2 (g) 2NO2 (g) • CO and H2O are neutral oxides. • Non-metal oxides are soluble in water. They dissolve in water to form acids. SO2 (g) + H2O (l) H2SO3 (aq) (Sulphurous acid) CO2 (g) + H2O (l) H2CO3 (aq) (Carbonic acid)
- 18. Metals with Water •Not all metals react with water. • Metals that react with water, produce metal oxide and hydrogen. If metal oxide is soluble in water, it produces metal hydroxide. Metal + Water Metal Oxide + Hydrogen Metal Oxide + Water Metal Hydroxide • Potassium and Sodium react with cold water violently. Reaction is exothermic and Hydrogen evolved catches fire. 2K (s) + 2H2O (l) 2KOH (aq) + H2 (g) + Heat 2Na (s) + 2H2O(l) 2NaOH (aq) + H2 (g) + Heat • Reaction of Calcium with water is less violent. Hydrogen does not catch fire. Calcium starts floating as Hydrogen sticks to the metal Ca (s) + 2H2O (l) Ca(OH)2 (aq) + H2 (g)
- 19. Metals with Water •Magnesium does not react with Cold water. It reacts only with hot water. It also starts floating as evolved Hydrogen sticks to the metal surface. ∆ Mg (s) + H2O (l) MgO (s) + H2 (g) • Aluminium, Iron and Zinc do not react with cold or hot water. But they can react with Steam to form Metal oxides and Hydrogen. 2Al (s) + 3H2O (g) Al2O3 (s) + 3H2 (g) 3Fe (s) + 4H2O (g) Fe3O4 (s) + 3H2 (g)
- 20. Activity 3.10 –How metals react with Water • Put Samples of small pieces of metals in beakers half-filled with cold water and observe. Metals that reacted with cold water Na, K, Ca Metals that produced Fire Na and K Metals that started floating after some time Ca and Mg Metals that reacted with Hot Water Mg Metals that reacted with Steam Al, Zn and Fe Metals that did not react with Steam also Pb, Cu, Ag and Au Reactivity of Metals: K > Na > Ca > Mg > Al > Zn > Fe > Pb > Cu > Hg > Ag > Au
- 21. Metals with Acid •Metals react with acids to give a salt and Hydrogen gas. Metal + Dilute Acid Salt + Hydrogen • Reaction of Metals with dilute Hydrochloric acid is explained in Activity 3.11 • When metals react with Nitric Acid, Hydrogen gas is not evolved. • This is because Nitric acid is an oxidizing agent which oxidizes Hydrogen to form water and it gets reduced to any of the Nitrogen Oxides. • Only Magnesium (Mg) and Manganese (Mn) react with very dilute HNO3 to evolve H2 gas.
- 22. Activity 3.11 –Observation of Metals reacting with dilute Acid • Put Samples of small pieces of metals (except Na and K) in separate test tubes containing dilute Hydrochloric acid Metal Reaction with HCl Reaction Rate of Reaction Mg dil. HCl Mg + 2 HCl → MgCl2 + H2 Very fast Al dil. HCl 2Al + 6 HCl → 2AlCl3 + 3H2 Fast Zn dil. HCl Zn + 2 HCl → ZnCl2 + H2 Fast Fe dil. HCl Fe + 2HCl → FeCl2 + H2 Slow Cu dil. HCl No reaction
- 23. Metals with Saltsolution of other metals • Not all metals are equally reactive. Reactive metals can displace less reactive metals from their compounds in solution or molten form. Metal A + Salt Solution Salt Solution + Metal B of Metal B of Metal A • In the above reaction, Metal A is more reactive than Metal B. This reaction is called displacement reaction.
- 24. Activity 3.12 –Reaction of Metals with Salt solution Displacement Reaction • • Conclusion: Iron is more reactive than Copper, there it displaces copper from its salt solution. Test Tube A • Iron nail dipped in CuSO4 Solution • Fe + CuSO4 (aq) → FeSO4 (aq) + Cu • Blue Colour → Green Colour • Reddish Brown Deposit of Cu on Iron Metal Test Tube B • Copper wire B dipped in FeSO4 solution • No reaction
- 25. Reactivity Series ofMetals K Potassium More Reactive Na Sodium Ca Calcium Mg Magnesium Al Aluminium Zn Zinc Reactivity Decreases Fe Iron Pb Lead Cu Copper Hg Mercury Ag Silver Au Gold Least Reactive
- 26. Reaction of Metaland Non-Metal Metals Non-Metals Cations Anions +ve ions -ve ions Ionic Bond Ionic Compound Lose electrons Gain electrons
- 27. Reaction of Metaland Non-Metal • For example, Sodium (Metal) and Chlorine (Non-metal) bond with each other as follows: Element Sodium Chlorine Symbols Na Cl Atomic No 11 17 Electronic Configuration 2, 8, 1 2, 8, 7 Ion formed Na+ Cl- Configuration of Ion 2, 8 2, 8, 8
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- 29. Properties of IonicCompounds Physical Nature Ionic Solids are hard due to strong force of attraction and generally brittle Melting Point & Boiling Point Have high Melting point and Boiling point This is because large amount of heat is required to break the strong Ionic attraction Solubility Soluble in water and insoluble in kerosene and petrol. Conduction of electricity Ionic compounds in solid state do not conduct electricity
- 30. Activity 3.13 –Properties of Ionic Compounds Salt Physical State Colour of Flame on heating Solubility in Conduction of ElectricityH2O Petrol Kerosene NaCl Solid Yellow √ x x Conducts electricity KI Solid Pale violet √ x x Conducts electricity BaCl2 Solid Pink to white √ x x Conducts electricity
- 31. Occurrence of Metals OccurrenceofMetals (ItoccursinEarth’scurst, seawater) Minerals Elementsor compounds occurring naturally in Earth’s crust. Ores Minerals that contain very high percentage of a particular metal. These metals can be extracted economically on large scale. e.g. Bauxite → Aluminium. Haematite → Iron
- 32. Occurrence of Metalsin Nature Metal Reactivity Series Occurrence Ore Metallurgy K Most Reactive Combine State Electrolysis Na Ca Mg Al Zn Moderately Reactive Combine State Sulphide, Oxide ores Calcination, Roasting Fe Pb Cu Least Reactive Free and Combine State Carbonate Ores RoastingHg Free State Sulphide or Oxide Ore Ag Au
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- 34. Conversion of Oreto Metal Oxide Calcination Roasting It is done for Carbonate Ores It is done for Sulphide Ores Heating of carbonate ores in absence of oxygen Heating of Sulphide ores in presence of oxygen CO2 gas is released and metal oxide is obtained SO2 gas is released and metal oxide is obtained ZnCO3 (s) → ZnO (s) + CO2 (g) Heat ZnS(s) + 3O2 → 2ZnO (s) + 2SO2(g) Heat
- 35. Extraction of MetalsLow in Activity Series 2Cu2S (s) + 3O2 (g) → 2Cu2O (s) + 2SO2 (g) 2Cu2O (s) + Cu2S → 6 Cu (s) + SO2 (g) 2HgS (s) + 3O2 (g) → 2HgO (s) + 2SO2 (g) 2HgO (s) → 2Hg (l) + O2 (g) Cinnabar Ore (HgS) Mercuric Oxide (HgO) Mercury Reduction (on further heating) Roasting Heating Heating Copper Sulphide (Cu2S) Copper Oxide (Cu2O) Copper Reduction (on further heating) Roasting Heating Heating
- 36. Extraction of Metalsin the Middle of Activity Series ZnCO3 (s) → 2ZnO (s) + 2SO2 (g) 2ZnO (s) + C (s) → Zn (s) + CO2 (g) 2ZnS (s) + 3O2 (g) → 2ZnO (s) + 2SO2 (g) 2ZnO (s) + C (s) → Zn (s) + CO2 (g) Zinc Sulphide (ZnS) Zinc Oxide (ZnO) Zinc Reduction (on heating with Coke) Roasting Heat Heat Zinc Carbonate (ZnCO3) Zinc Oxide (ZnO) Zinc Reduction (on heating with coke) Calcination Heat Heat
- 37. Thermite Reaction • Apartfrom using coke to reduce metal oxides to metals, displacement reactions can also be used. • Highly reactive metals such as Sodium, Calcium, Aluminium are used as reducing agents and displace metals of lower reactivity than them from the metal oxides. • For example, when Manganese dioxide is heated with Aluminium powder, Aluminium displaces Manganese as follows. 3MnO2 (s) + 4Al (s) 3 Mn (l) + 2Al2O3 (s) + Heat • These displacement reactions are highly exothermic that the metals produced will be in molten state. Fe2O3 (s) + 2Al (s) 2 Fe (l) + Al2O3 (s) + Heat • This phenomenon is used to join railway tracks.
- 38. Extraction of Metalsin Top of Activity series HighlyReactiveMetals They have more affinity for Oxygen than Carbon. They cannot be obtained from their compounds by heating with carbon. For e.g. Carbon cannot reduce oxides of Sodium, Magnesium, Calcium etc. These metals are obtained by electrolytic reduction. At cathode Na+ + e- → Na At anode Cl- → Cl + e- Molten Chlorides of Highly reactive metals Metals are deposited at cathode Chlorine is liberated at anode Electrolytic Reduction
- 39. Refining of Metals- Electrolysis • A strip of impure metal (to be refined) is taken as anode. • Pure metal (Small Strip) of same material is taken as Cathode. • Electrolyte of same metal solution is used. • When electric current is passed, pure metal is deposited at Cathode. • Impurities are collected at the bottom of anode (anode mud)
- 40. Corrosion • Metals whenleft open in air gets corroded. • Silver + Sulphur in air Silver Sulphide (black coat) • Copper + Carbon dioxide in air Copper carbonate (green coat) • Iron + Air and Moisture Iron oxide (rust) (Brown flaky)
- 41. Prevention of Corrosion •By applying paint • By applying oil / grease • Galvanizing a metal Coating of zinc on metal • Anodizing a metal Coating a layer of Aluminium Oxide on Aluminium • By making alloys Steel - (Fe + Ni + Cr) Brass - (Cu + Zn) Bronze – (Cu + Sn)
- 42. Activity 3.14 –Rusting of Iron Nails • Take three test tubes A, B, C and place clean Iron nails. Test tube A – water Test tube B – Distilled water + 1 ml of oil Test tube C – anhydrous Calcium chloride
- 43. Activity 3.14 –Rusting of Iron Nails • Leave these test tubes for a few days and then observe. Observation: Nails in Test tube A rusts. Iron Nails in Test tubes B & C does not rust Reason: Nails in Test tube A exposed to air and water Nails in Test Tube B does not get exposed to air due to layer of oil Nails in Test Tube C Does not get both air and water Conclusion: Both air and water are required for iron nails to form rust.