• Elementscanbeclassifiedasmetalsandnon-metalsonthebasisoftheirproperties. • Exampleofsomemetalsare: Iron(Fe),Aluminium(Al),Silver(Ag),Copper(Cu) • Examplesofsomenon-metalsare: Hydrogen(H),Nitrogen(N),Sulphur(S),Oxygen(O)

I. PHYSICAL PROPERTIES

PROPERTY METALS NON-METALS

1.Lustre Metalshaveshiningsurface. They do not have shiningsurface.•ExceptIodine.

2.Hardness Theyaregenerallyhard.•ExceptSodium,LithiumandPotassiumwhich are soft and can be cut withknife.

Generallysoft.• Except Diamond, a formof carbon which is thehardestnaturalsubstance.

3.State Existassolids.•ExceptMercury.

Existassolidsorgaseous.•ExceptBromine.

4.Malleability Metalscanbebeatenintothinsheets.•GoldandSilverarethemostmalleablemetals.

Non-metals are non-malleable.

5.Ductility Metalscanbedrawnintothinwires. Theyarenon-ductile.

6.Conductorofheat&elec-tricity

Metalsaregoodconductorsofheatandelectricity.

• Silver (Ag) and Copper (Cu) : Bestconductorsofheat.

• Lead (Pb), Mercury (Hg) poorconductorofheat.

Non-metals are poorconductor of heat andelectricity.•ExceptGraphite.

7.Density Generally have high density and highmeltingpoint.

•ExceptSodiumandPotassium.

Have low density and lowmeltingpoint.

8.Sonorous Metals produce a sound on striking ahardsurface.

Theyarenotsonorous.

9.Oxides Metallicoxidesarebasicinnature. Non-metallic oxides areacidicinnature.

II. CHEMICAL PROPERTIES OF METALS(A) Reaction with Air : Metalscombinewithoxygentoformmetaloxide. Metal+O2 →Metaloxide Examples : (i) 2Cu+O2 →2CuO

Copper

oxide

(black)

(ii) 4Al+3O2 →2Al2O3 Aluminiumoxide

(iii) 2Mg+O2 →2MgO DifferentmetalsshowdifferentreactivitiestowardsO2. • NaandKreactsovigorouslythattheycatchfireifkeptinopensotheyarekept

immersedinkerosene. • SurfacesofMg,Al,Zn,Pbarecoveredwithathinlayerofoxidewhichprevent

themfromfurtheroxidation. • Fedoesnotburnonheatingbutironfillingsburnvigorously. • Cudoesnotburnbutiscoatedwithblack oxide.copper

• AuandAgdoesnotreactwithoxygen.

Amphoteric Oxides : Metaloxideswhichreactwithbothacidsaswellasbases to producesaltsandwaterarecalledamphotericoxides.

Examples:Al2O3+6HCl→2AlCl3 + H2O Al2O3+2NaOH→2NaAlO2 + H2O SodiumAluminate(B) Reaction of Metals with Water : Metal+Water→Metaloxide+Hydrogen Metaloxide+Water→Metalhydroxide

ReactwithcoldH2ONa,K,Ca

Reactwithsteam ReactwithhotH2O Al,Fe,Zn Mg

Metals

NoreactionwithH2O CaandMgfloatas Pb,Cu,Au,Ag bubblesofH2 sticktotheirsurface Examples : (i) 2Na+2H2O→2NaOH+H2 + Heat (ii)Ca+2H2O→Ca(OH) 2 + H2

(iii)Mg+2H2O→Mg(OH)2 + H2

(iv)2Al+3H2O→Al2O3 + 3H2

(v)3Fe+4H2O→Fe3O4 + 4H2

(C) Reaction of Metals with Acids (Dilute) : Metal+Diluteacid→Salt+H2 Cu,Ag,Hgdonotreactwithdil.acids. Examples : (i) Fe+2HCl→FeCl2 + H

2 (ii)Mg+2HCl→MgCl2 + H2

(iii)Zn+2HCl→ZnCl2 + H2

(iv)2Al+6HCl→2AlCl3 + 3H2

(D) Reaction of Metals with Solutions of other Metal Salts : MetalA+SaltsolutionB→SaltsolutionA+MetalB • Reactivemetalscandisplacelessreactivemetalsfromtheircompoundsinsolution

form. Fe + CuSO4 → FeSO4 + Cu

REACTIVITY SERIES Thereactivityseriesisalistofmetalsarrangedintheorderoftheirdecreasingactivities. K Mostreactive Na Ca Mg Al Zn Reactivitydecreases Fe Pb H Cu Hg Ag Au Leastreactive

Reaction of Metals with Non-metals • Reactivityofelementsisthetendencytoattainacompletelyfilledvalenceshell. • Atomsofthemetalsloseelectronsfromtheirvalenceshelltoformcation.Atomof

thenon-metalsgainelectronsinthevalenceshelltoformanion. E.g., FormationofNaCl Na→Na+ + e-

2,8,1 2,8 Sodiumcation

Cl+e− → Cl-

2,8,7 2,8,8

Chlorideanion

Ionic Compounds Thecompoundsformedbythetransferofelectronsfromametaltoanon-metalare

calledioniccompoundsorelectrovalentcompounds.Properties of Ionic Compounds 1. Physical nature : Thearesolidandhard,generallybrittle. 2. Melting and Boiling Point : Theyhavehighmeltingandboilingpoint. 3. Solubility : Generallysolubleinwaterandinsolubleinsolventssuchaskerosene,

petroletc. 4. Conduction of electricity : Ionic compounds conduct electricity inmolten and

solutionformbutnotinsolidstate.

Occurrence of Metals Minerals : Theelementsorcompoundswhichoccurnaturallyintheearth’scrustare

calledminerals. Ores : Minerals thatcontainveryhighpercentageofparticularmetalandthemetal

canbeprofitablyextractedfromit,suchmineralsarecalledores.

reactivemetals Ca Notfoundinfreestatebyelectrolysis

reactive Pb Occurassulphides,oxides,carbonatesbyusingcarbon

greactive Au Occurinnative/freestate

Extraction of Metals from OresStep 1. Enrichmentofores.Step 2. Extractionofmetals.Step 3. Refiningofmetals.

ORE

Concentrationofore

Metalswithhigh Metalsofmedium Metalsoflow reactivity reactivity reactivity

Electrolysisofmoltenore Sulphideores

Carbonateore Sulphideore e.g.,ZnCO3 e.g.,HgS(cinnabar),ZnS (inlimitedair) (excessair) PureMetal Calcination Roasting Roasting Oxidesofmetal

Reductiontometal Metal

Purificationofmetal RefiningSteps Involved in Extraction of Metals from Ores

Some Important Terms

(a) Gangue : Oresareusuallycontaminatedwithlargeamountofimpuritiessuchassoil,sandetc.calledgangue.

(b) Roasting : The sulphide ores are converted into oxides by heating strongly in thepresenceofexcessair.Thisprocessiscalledroasting.

2ZnS+3O2 Heat→ 2ZnO+2SO2

(c) Calcination : Thecarbonateoresarechangedintooxides byheatingstronglyinlimitedair.Thisprocessiscalledcalcination.

ZnCO3 Heat→ ZnO+CO2

(d) Reduction : Metaloxidesarereducedtocorrespondingmetalsbyusingreducingagentlikecarbon. ZnO+C→Zn+CO

Refining of Metals

Themostwidelyusedmethodforrefiningimpuremetaliselectrolyticrefining.

•Anode:Impurecopper •Cathode:Stripofpurecopper •Electrolyte:Solutionofacidifiedcoppersulphate (a)Onpassingthecurrentthroughelectrolyte,theimpuremetalfromanodedissolvesinto

theelectrolyte. (b)Anequivalentamountofpuremetalfromtheelectrolyteisdepositedatthecathode. (c)Theinsolubleimpuritiessettledownatthebottomoftheanodeandiscalledanode

mud.Corrosion Thesurfaceofsomemetalssuchasironiscorrodedwhentheyareexposedtomoistair

foralongperiodoftime.Thisiscalledcorrosion. (i) Silverbecomesblackwhenexposedtoairasitreactswithairtoformacoatingof

silversulphide. (ii)Copperreactswithmoistcarbondioxideintheairandgainsagreencoatofcopper

carbonate. (iii)Ironwhenexposedtomoistairacquiresacoatingofabrownflakysubstancecalled

rust.

Prevention of Corrosion Therustingofironcanbepreventedbypainting,oiling,greasing,galvanizing,chrome

plating,anodizingormakingalloys. Galvanization : Itisamethodofprotectingsteelandironfromrustingbycoatingthem

withathinlayerofzinc. Alloy : Analloyisahomogenousmixtureoftwoormoremetalsorametalandanon-

metal. Iron :Mixedwithsmallamountofcarbonbecomeshardandstrong. Steel : Iron+Nickelandchromium Brass : Copper+Zinc Bronze : Copper+Tin(Sn) Solder : Lead+tin

Amalgam : Ifoneofthemetalis mercury(Hg).

QUESTIONS1. Whatisthedifferencebetweenamineralandanore?2. Differentiatebetweenroastingandcalcinationsprocessinmetallurgy.3. What is an alloy ? Name the alloy which has iron, nickel and chromium as its

constituent.Whatisthechiefuseofthisalloy?4. Explainanytwowaystopreventrustingofiron.

Hints To Questions1. Mineral Ore Naturaloccurringchemical Anoreisamineralfrom

substancesobtainedbymining whichmetalisobtained.2. Roasting Calcination (a)Oreisheatedinthe (a) Oreisheatedin presenceofair. absenceofair. (b)Convert (b) Convert

SulphideoreRoasting→ OxideoreCarbonateore

Calcination→ Oxideore

3. Alloy : Itisahomogenoussolidsolutionofonemetalwithoneormoremetalsornon-metals.

Stainlesssteel,usedformakingutensils,equipments.4. (a)Bycoatingthesurfacewithathinfilmofoilorgrease. (b)Bypaintingthesurface. (c)Bytheprocessofgalvanization.