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PHYSICAL PROPERTIES OF METALS AND NON-METALS, , On the basis of their properties, all the elements can, be divided into two main groups: metals and nonmetals. Apart from metals and non-metals, there are, some elements which show characteristics of both, metals and non-metals and known as metalloids, for, example, Si, Ge, As, Sb and Te., , Metals are opaque, lustrous elements that are good, conductors of heat and electricity. Examples: Copper,, tron, Silver, Aluminium, etc., , Non-metals are the elements that have properties, which are different from those of metals. Examples:, Carbon, Nitrogen, Oxygen, Sulphur etc., , Phusical Properties of Metals, , (1) State: Metals are generally solids at room, temperature except mercury which is a liquid., , (2) Lustre: In pure state metals have a shining, surface. Al and Mg are white whereas Au is, yellow and Cu is reddish brown in colour., , (3) Hardness: Metals are generally hard but, hardness varies from metal to metal., , (4) Malleability: Some metals can be beaten into, thin sheets and this property is called malleability., Gold and silver are the most malleable metals., , (8) Ductility: Some metals can be drawn into very, thin wires and this property is called ductility., Gold is the most ductile metal., , (6) Thermal and electrical conductivity: Metals are, generally good conductors of heat and electricity., Silver is the best conductor of heat followed by, copper and aluminium. Silver and copper are the, best conductors of electricity., , (7) Melting and Boiling points: Metals generally, have high melting and boiling points. The boiling, and melting points of aluminium are 933 K and, 2792 K respectively., , (8) Sonorous: Metals that produce a sound on, striking a hard surface are said to be sonorous,, , Example 1. Case Based:, , A student took an aluminium or copper wire and, clamped this wire on a stand, as shown in Fig. 1., , , , , Metal wire, , '4—Free end, of wire, , Pin, , Wax, , Fig. 1, , He then fixed a pin to the free end of the wire using, wax and heated the wire with a spirit lamp, candle or, a burner near the place where it is clamped., Another student set up an electric circuit as shown, in Fig. 2 below to test the electrical conductivity of, metals. He placed the metal to be tested in the circuit, between terminals A and B as shown., , [NCERT Activity 3.5, 3.6], , , , , , , Switch, =—___ (*), A t B, , Insert sample, , to be tested, , , , Fig. 2, (A) The activity performed by the first student, (Fig.1) shows that:, , (a) Metals are good conductors of heat and, have low melting points., , (b) Metals are poor conductors of heat and, have high melting points., , (c) Metals are good conductors of heat and, have high melting points., , (d) Metals are poor conductors of heat and, have low melting points., , (B) The metals which are poor conductors of, heat are:, , (a) Lead and zinc, , (b) Mercury and zinc, (c) Lead and tin, , (d) Lead and mercury, , (C) What conclusion can be drawn from the, activity performed by the second student, (Fig.2)?, , (D) Name the two best conductors of electricity., , (E) Assertion (A): Metal such as aluminium, , is used for making cooking, utensils., , Aluminium is a highly ductile, , metal., , (a) Both (A) and (R) are true and (R) is the, correct explanation of the (A)., , (b) Both (A) and (R) are true, but (R) is not the, correct explanation of the (A)., , Reason (R):

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|, , (c) (A) is true, but (R) is false., (d) (A) is false, but (R) is true., , ans. (A) (C) Metals are good conductors of heat and, , have high melting points., , Explanation: Metals have a high melting point, and are generally good conductors of heat., Most metals are also good conductors of, electricity., , (B) @ Lead and mercury, , Explanation: The metals lead and mercury, are comparatively poor conductors of heat,, Whereas the best conductors of heat are silver, and copper., , (C) The conclusion that can be drawn from the, activity performed by the second student (Fig.2), is that the bulb glows when a metal is inserted, between A and B showing that most of the, metals conduct electricity., , (D) Silver and copper are the best conductors of, electricity., , (©) (6) Both (A) and (R) are true, but (R) is not, the correct explanation of the (A)., Explanation: Metal such as aluminium is, used for making cooking utensils as it is a, good conductor of heat and has high melting, point. The property of metals used for making, electrical wires are ductility and good electrical, , conductivity., , Physical Properties of Non-Metals, , (@, , (2), , (3), , (4), , (5), (6), , (7), , State: Non-metals are either solids or gases, except bromine which is a liquid., , Lustre: Non-metals do not have any lustre., Hardness: Non-Metals are generally soft., Exceptions: Diamond is an allotrope of carbon, and is the hardest natural substance, Malleability: Non-metals are not malleable,, Actually they are brittle,, , Ductility: Non-metals are not ductile also., Thermal and electrical Graphite, which is, an allotrope of Carbon conducts electricity., Therefore, this is an execption. do not conduct, heat and electricity., , Melting and boiling points: Non-metals have, low melting and boiling points., , Example 2. You are given a hammer, a battery, a, bulb, wires and a switch,, , _ A) How could you use them to distinguish, , between samples of metals and non-metals?, , i), , Assess the usefulness of these tests in, distinguishing between metals and nonmetals, [NCERT], , Ans. (A) Metals and non-metals have different, , physical properties. If we take the given samples, and strike them with a hammer, metals will be, converted into sheet, whereas non-metals will, not. This is because metals are malleable., , Also, metals are sonorous and produce sound, when hit with a hammer, whereas non-metals, are not sonorous., , The battery, wires, bulb and switch can be, arranged in the form of a circuit for testing, the electrical conductivity of samples, (refer to Fig. 2)., , When sample of metals are inserted between A, and B, the bulb glows which shows that metals, are good conductors of electricity, whereas, the bulb does not glow when samples of nonmetals are inserted which shows that nonmetals are poor conductors of electricity., , (B) These tests are useful in distinguishing, between metals and non-metals based on the, differences in properties of metals and nonmetals as metals are malleable, sonorous and, good conductors of electricity whereas nonmetals do not possess any of these properties., , Exceptions in Physical Properties, , , , , , , , Physical Property Exception’, , (1) | Physical State | Mercury is a metal that is a, liquid at room temperature., | Bromine is a non-metal that, , is liquid at room temperature., , (2) | Melting Point | Sodium, potassium, cesium, , , , and Boiling | and gallium are metals that, point have low melting points. Diamond is a non-metal which, , has a high melting point., (3) | Density Alkali metals (lithium, sodi, um, potassium) are so soft, that they can be cut with a, knife., , Electrical Con, , , Mercury, a metal, offers a, , , , , , ductivity very high resistance to the, Passage of current., (5) | Lustre lodine is a non-metal which, , , , is lustrous.

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| Topic 2 |, , CHEMICAL PROPERTIES OF METALS, , Metals are electropositive in nature as they lose, electrons and form positive ions., , K—> K'+ @&, Ca—> Ca?* + 267, , Non-metals are electronegative in nature as they, actept electrons and form negative ions., , Cl+e—> Cl, , $4 2e-—> S?, Most non-metals produce acidic oxides, Examples: SO», CO2, Most metals produce basic oxides. Examples: Na2O,, Cad, , Chemical Properties of Metals, , Reaction with Oxygen, Metals combine with oxygen to form basic or, amphoteric oxides., , Metal + Oxygen —> Metal Oxide, 2Cu + O2 —> 2CuO (Copper oxide), 4Al+ 30,—> 2AL03, Although metal oxides are basic in nature but some, metals show both acidic and basic nature., Amphoteric oxides: The metal oxides which show, both acidic and basic nature are known as amphoteric, oxides., For example, aluminium oxide and zinc oxide are, amphoteric oxides., , Examples:, , The reaction of aluminium oxide with acids and bases, is given below:, Al,O3 + 6HCL —> 2AICl3 + 3H20, AlL,O3 + 2NaOH —> 2NaAlO, +H2O, , Alkalies: The oxides of most metals are insoluble in, water but some of these dissolve in water to form, alkalies., Examples: Sodium oxide and potassium oxide, Naz0@ +20) —> 2NaOH¢q), K20( + H20() —> 2KOH (aq), , Reaction of different metals with oxygen: Different, metals show different reactivities towards oxygen., , (1) The reaction of alkali metals such as potassium, and sodium with oxygen is so vigorous that they, are kept immersed in kerosene oil to prevent, accidental fires in case they are kept in open., , (2) The surfaces of metals such as magnesium,, aluminium, zinc, lead, etc, are covered with a thin, layer of oxide at ordinary temperature, which, , AND NON-METALS, , prevents the metal from further oxidation and jg, therefore a protective layer., , (3) Iron does not burn on heating but iron filings, burn vigorously when sprinkled in the flame of q, burner., , (4) Copper does not burn, but the hot metalis coated, with a black coloured layer of copper (II) oxide., , (5) Silver and gold do not react with oxygen even at, high temperatures., , Anodising: Anodising is a process of forming a thick, oxide layer of aluminium. Aluminium forms athin oxide, layer when exposed to air which makes it resistant to, further corrosion. During anodising, a clean aluminium, article is made the anode and is electrolysed with dil, HSO,. The oxygen gas evolved at the anode reacts, with aluminium to form a thicker protective oxide, layer., Example 3. An element reacts with oxygen to, give a compound with a high melting point. This, compound is also soluble in water. The element is, likely to be:, (a) Calcium, (c) Silicon, Ans. (a) Calcium, Explanation: As the compound has a high, melting point, it is an ionic compound. Since, metal oxides are ionic in nature, therefore, the, element could be calcium or iron., However, it is also given that the compound, is also soluble in water and as calcium oxide, is soluble in water, whereas iron oxide is not, soluble, the given element is calcium., 2Ca() + Org) —> 2Ca0¢), CaO + HzO —> 2Ca(OH) (aq) + Heat, , (b) Carbon, , (d) Iron [NCERT], , Reaction with Water, , Metals react with water and produce a metal, hydroxide or oxide and hydrogen gas is evolved., , Metal + Water —> Metal oxide + H>, , Metal oxides that are soluble in water dissolve in it to, further form metal hydroxide., , Metal oxide + Water —> Metal hydroxide, , (1) Metals like K and Na react violently with cold, water., , 2K(q + 2H20( —> 2KOH (aq) + Haq) + Heat, 2Nag + 2H20() —> 2NaOH (aq) + Haig) + Heat, (2) The reaction of calcium with water is less violent., Ca + 2H30 —> Ca(OH), + Hp, Calcium starts floating because the bubbles of

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(3), , (4), , (5), , hydrogen gas formed stick to the surface of the, , metal., Mg does not react with cold water but reacts with, , hot water to form Mg(Oh)». It also starts floating, because the bubbles of hydrogen gas formed, stick to the surface of the metal., Metals like Al, Zn and Fe react with steam to form, ametal oxide,, , 2Ale) + 3H20@) —> Al,03%) + 3H2@), , 3Fei) + 4H20¢6) —> Fe30.4¢ + 4H20@), Metals like Pb, Cu, Ag and Au do not react with, water at all., , Example 4. Case Based:, , Collect the samples of following metals: aluminium,, copper, iron, lead, magnesium, zine and sodium. Put, small pieces of the samples separately in beakers, half-filled with cold water. Put the metals that, , did, , not react with cold water in beakers half-filled, , with hot water. For the metals that did not react, with hot water, arrange the apparatus as shown, in ig. 3 and observe their reaction with steam., , Glass-wool, , A, , (), , [NCERT Activity 3.10], , , , Metalsample—, , , , soaked in, water, , Burner, , , Fig. 3 Action of steam on a metal, Select the metals which react with cold water:, MAL (ll) Mg, (i) Na (lV) K, (a) Both (I) and (il), (b) Both (1) and (ill), (c) Both (II) and (IV), (A) (0), (Ml) and (IV), A metal X when treated with cold water gives, the metal hydroxide Y and starts floating., , The metal X and compound Y could be:, , , , , , , , , , , , , , | MetalX ‘Compound Y _, oO. Mg Mg(OH)2, (| Ca | —_CaOH)2, [ip | Na | NOH, Wy) | k Roth, Select the correct option:, (2) Only () (b) Only (I), , (©) Both (1) and (Ill) (d) Both (II) and (IV), , (©), , (0), , «), , Ans., , Name the metals which do not react either, with cold or hot water., , Arrange the metals aluminium, copper,, iron, lead, magnesium, zinc and sodium in, decreasing order of their reactivity with, water., , Assertion (A): Sodium catches fire when it, reacts with hot water., , The reaction between sodium, and cold water is highly, exothermic., (a)Both (A) and (R) are true and (R) is the, correct explanation of the (A)., (b) Both (A) and (R) are true, but (R) is not the, correct explanation of the (A)., (c) (A) is true, but (R) is false., (d) (A) is false, but (R) is true., (A) (©) Both (Ill) and (IV), Explanation: Metals like K and Na react violently, with cold water., 2K) + 2H2O() —> 2KOH (aq) + Haq) + Heat, , 2Naj)+ 2H209 —> 2NaOH aq) + Haq) + Heat, Mg does not react with cold water but reacts, with hot water to form Mg(OH)>., Alreacts with steam to form a metal oxide., , 2Als + 3H20@) —> Al03@ + 3H2@), , (B) (b) Only (I), Explanation: Out of the metals Mg, Ca, Na and, K, both Na and K react so violently with water, that the hydrogen gas evolved immediately, catches fire., The reaction of Ca with cold water is less violent, , and calcium starts floating because the bubbles, of hydrogen gas formed stick to the surface of, , the metal., Ca + 2H2O—-> Ca(OH)> + Ho, , Mg does not react with cold water but reacts, with hot water to form Mg(OH)> and hydrogen., (C) The metals Al, Zn and Fe do not react either, with cold or hot water but they react with steam, to form the metal oxide and hydrogen gas., , 2A\(s) + 3H20@) —> AlgO3@) + 3H2@), , 3Fe() + 4H20(g) —> Fe304¢ + 4H), (D) The decreasing order of reactivity of metals, with water is;, , Na>Mg>Al>Zn>Fe>Pb>Cu, , (E) (d) (A) is false, but (R) is true., Explanation: Sodium reacts violently even with, cold water and the reaction is such a highly, exothermic reaction that the hydrogen gas, evolved immediately catches fire., , Reason (R):

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Example 5. Give reasons why copper is used to, make hot water tanks and not steel (an alloy of, iron). [NCERT], Ans. Steel is an alloy of iron and iron reacts with, steam to form Fe304., 3Fey + 4H20@) — Fe304i6) + 4H 39), However, copper is less reactive and does not, react either with cold water, hot water or steam., Therefore, copper is used to make hot water, tanks being less reactive than iron., , Reaction with Acids, , (1) When a metal reacts with dil HCl and dil H2SO4, a, , salt is formed and H2 gas is evolved., Metal + Dil. Acid ——> Salt + Hydrogen, ZN eg + ZNSO4(eq) —> ZNSO4(aq + H2, , (2) Hp gas is not evolved when a metal reacts with, HNOs (nitric acid) as HNO is a strong oxidizing, agent and oxidizes the H produced to water and, is itself reduced to any of the oxides of nitrogen., Exceptions: Magnesium and Manganese., , (3) The reactivity of all metals towards acids is not, the same and can be found out from the rate at, which bubbles of hydrogen gas are formed and, the amount of heat generated. Amongst Al, Mg,, Fe and Zn, the reactivities towards acids is: Mg >, Al> Zn> Fe, , (4) Aqua regia: It is a freshly prepared mixture of, conc. HCl and conc. HNO; in the ratio of 3:1. It is, a highly corrosive, fuming liquid which can even, dissolve gold and platinum, even though neither, of these acids can do so alone., , Re Important, , Metals such as copper, mercury, silver and gold,, which are placed below hydrogen in the reactivity, series of metals, do not react with dilute acids., , Example 6. A man went door-to-door posing as a, goldsmith. He promised to bring back the glitter of, old and dull gold ornaments. An unsuspecting lady, gave a set of gold bangles to him which he dipped in, a particular solution. The bangles sparkled like new, but their weight was reduced drastically. The lady, was upset but after a futile argument the man beat, a hasty retreat. Can you play the detective to find, out the nature of the solution he had used? [NCERT], Ans. The man used aqua regia which is a mixture, of conc, HCl and conc. HNO3 acids in the ratio, 3:1 and has the property of dissolving gold., When the unsuspecting lady gave a set of gold, bangles to the man, he dipped them in aqua, regia solution due to which some gold dissolved, in the solution bringing back the sparkle but at, the same time the weight of gold bangles was, reduced as it went into the solution., , Example 7. Name two metals which will displace, , hydrogen from dilute acids, and two metals which, , will not. INCERT], , Ans. Two metals which will displace hydrogen from, , dilute acids are magnesium and aluminium, ang, two metals which will not displace hydrogen are, copper and silver., , Reaction of Metals with Solutions of Other, , Metal Salts ;, , (1) Reactive metals displace less reactive metals, from their compounds in solution or molten form,, Displacement reactions give better evidence, about the reactivity of metals. If metal A displaces, metal B from its solution, it is more reactive than, B., , Metal A + Salt solution of B—> Salt solution of A, + Metal B, , (2) If we put an iron nail in a solution of copper, sulphate, we observe that the blue colour of, copper sulphate solution in the test tube fades, gradually and red-brown copper metal is formed., The reaction taking place is:, , CuSO4(aq) + Fe) — FeSO4(aq) + Cu), However, no reaction takes place if a strip of, copper metal is placed in iron sulphate solution, because copper is less reactive than iron and, hence cannot displace iron from iron sulphate, solution., , Ge Important, , + Some examples of reaction of metals with solutions of, other metal salts., , , , mE? ;, , S. | Example of Reaction of, No. | Metal with solution of, Metal Salt xX, , Chemical Equation —, , , , (1) |Reaction of zinc with|CuSO4(aq + ZN) —>, | copper sulphate solution |ZnSO.(aq) + Cue), , (2) |Reaction of copper with| 2AgNO3(aq + Cug —>, silver nitrate solution Cu(NO2)2(aq + 2AG(), , \ If zinc oxide, magnesium oxide and copper oxide were, heated, turn by turn, with zinc, magnesium and copper, metals, we can note down the displacement reactions taking, place as shown:, , , , , , , , , , , , , , , , , , , , 2 ell <, i Re ae a], MetalOxide = Zinc “Magnesium Copper, (1) Zinc Oxide - Displace- ment, (2) Magnesium - = A, __ Oxide, (3) Copper Displacement Displace- =, oxide ment, , , , , , , , , , , , , , Activity Series (The Relative Reactivities of Metals):, The metals have been arranged in order of their