MATERIALS : METALS AND NON-METALS Y

1 MATERIALS : METALS AND NON-METALSMATERIALS : METALS AND NON-METALSYou are familiar with a number ofmaterials like iron, aluminium ,copper, etc. Some MATERIALS havebeen given in Table similar change if we try to beat awood log ?Let us find a small iron nail, a coal piece,a piece of thick aluminium wire anda pencil lead. Beat the iron nail witha hammer (Fig. ). (But take carethat you don t hurt yourself in theprocess.) T ry to hit hard. Hit : Appearance andHardness of MaterialsObject/AppearanceHardnessMateri al(Shiny/Dull)(Very hard/Not veryhard)IronCoalSulphurAluminiumCopper- ----Can you name the MATERIALS whichare METALS ? The rest of the MATERIALS inTable are non- METALS .

2 METALS can bedistinguished from non- METALS on thebasis of their physical and chemicalproperties. Recall that lustre andhardness are physical Properties ofMetals and Non-metalsHave you ever seen a blacksmith beatingan iron piece or an article made up ofiron, like a spade, a shovel, an axe? Doyou find a change in the shape of thesearticles on beating? Would you : Malleability of MaterialsObject/Change in ShapeMaterial(Flattens/Breaksinto pieces)Iron nailCoal pieceAluminium wirePencil leadthe aluminium wire also. Thenrepeat the same kind of treatmenton the coal piece and pencillead. Record your observations inTable : Beating an iron nail with hammer2015-16 (11-11-2014)Fig.

3 : Electric testerWhere do you find the use ofaluminium and copper wires? Have youseen wires of coal? Definitely not!The property of metal by which it canbe drawn into wires is called you ever noticed the differencein sound on dropping an iron sheet/plate, a metal coin, and a piece of coalon the floor? If not, you can try it you note any difference in the soundproduced?Oh! The meaning of recallingour experiences and then ofthis activity was to show thatmetals are good conductors ofheat and electricity. We learntthis in Class : METALS AND NON-METALS45 You saw that the shape of the iron nailand the aluminium wire changed onbeating.

4 If they were beaten harder thesecould be changed into sheets. You mightbe familiar with silver foil used fordecorating sweets. You must also befamiliar with the aluminium foil used forwrapping food. The property of METALS bywhich they can be beaten into thin sheetsis called malleability. This is acharacteristic property of METALS . As youmust have noticed, MATERIALS like coal andpencil lead do not show this property. Canwe call these METALS ?Can you hold a hot metallic pan whichis without a plastic or a wooden handleand not get hurt? Perhaps not! Why? Tryto list some other experiences in which awooden or plastic handle protects youfrom being hurt while handling hotthings.

5 On the basis of these experienceswhat can you say about the conductionof heat by wood and plastic?You must have seen an electricianusing his screw driver. What kind ofhandle does it have? Why?Let us find how to make an electriccircuit to test whether electricity canpass through an object or not(Fig. ). You might have performedthe activity with various objects inClass VI. Now, repeat the activitywith the MATERIALS mentioned inTable Observe and group thesematerials into good conductors andpoor : Electrical Conductivityof Conductor /Poor wireYou observe that iron rod, nail andcopper wire are good conductors whilerolled sulphur piece and coal piece arepoor (11-11-2014)SCIENCE46 Have you seen wooden bells intemples?

6 Can you give a reason?The things made of METALS producea ringing sound when struck you have two boxes similar inappearance, one made of wood and theother of metal. Can you tell which boxis made of metal by striking both theboxes?Since METALS produce ringingsounds, they are said to be MATERIALS other than METALS are performing the above activities,we can say that some MATERIALS are hard,lustrous, malleable, ductile, sonorousand good conductors of heat andelectricity. The MATERIALS whichgenerally possess these properties arecalled METALS . The examples of metalsare iron, copper, aluminium , calcium,magnesium, etc. In contrast, materialslike coal and sulphur are soft and dullin appearance.

7 They break down into apowdery mass on tapping with ahammer. They are not sonorous and arepoor conductors of heat and MATERIALS are called examples of non- METALS are sulphur,carbon, oxygen, phosphorus, rust is formed. You had alsoperformed in Class VII an activity ofburning a magnesium ribbon in air. Youhad learnt that in both the processesoxide formation takes place. Completethe following reactions of iron andmagnesium with (Fe) + Oxygen (O2) + Water (H2O) ?Magnesium (Mg) + Oxygen (O2) ?Activity us check the nature of rustformed as a result of the reactionbetween iron, oxygen and a spoonful of rust anddissolve it in a very little amount ofwater.

8 You will find that the rustremains suspended in water. Shakethe suspension well. Test thesolution with red and blue litmuspapers (Fig. ). What do youobserve? Is the solution acidic orbasic? METALS like sodium and potassium aresoft and can be cut with a is the only metal which isfound in liquid state at roomtemperature. These are Properties ofMetals and Non-metalsReaction with OxygenYou are familiar with the phenomenonof rusting of iron. Recall the reaction byRustRustsuspensionRed litmuspaperFig. : Testing the nature of rust2015-16 (11-11-2014) MATERIALS : METALS AND NON-METALS47 Fig. (a) : Burning of sulphur powderImproviseddeflagratingspoonNow recall the activity of burningmagnesium ribbon.

9 The ash obtainedon burning magnesium ribbon isdissolved in water and tested for itsacidic/basic the solution acidic or basic? Howdo you ascertain this?You must have observed that the redlitmus turns blue. So, oxide of magnesiumis also basic in nature. In general, metallicoxides are basic in us now observe the reaction ofnon- METALS with (To be demonstrated by the teacherin the class)Take a small amount of powderedsulphur in a deflagrating spoon andheat it. If deflagrating spoon is notavailable, you may take a metallic capof any bottle and wrap a metallic wirearound it and give it the shapeshown in Fig. (a).As soon as sulphur starts burning,introduce the spoon into a gas jar/glass tumbler [Fig.]

10 (a)]. Cover thetumbler with a lid to ensure thatthe gas produced does not the spoon after some a small quantity of water intothe tumbler and quickly replace thelid. Shake the tumbler well. Checkthe solution with red and bluelitmus papers [Fig. (b)].When a copper vessel is exposed tomoist air for long, it acquires a dullgreen coating. The green material isa mixture of copper hydroxide(Cu(OH)2) and copper carbonate(CuCO3). The following is the reaction2Cu+H2O+CO2+O2 Cu (OH)2 + CuCO3 moist airDoes copper also getrusted? I have seena greenish depositon the surface ofcopper (b) :Testing of solution with litmuspapers2015-16 (11-11-2014)SCIENCE48 The name of the product formed inthe reaction of sulphur and oxygen issulphur dioxide gas.