UNIT 3 COMPARISON & CONTRAST Vocabulary Properties of Materials (Adj / Nouns / Vbs) WORD FORMATION: N/VB from ADJ Grammar and functions Comparison: special structures ADJ vs ADV Comparing & Contrasting: connectors

PROPERTIES OF MATERIALS COPPER A non-ferrous metal high electrical and thermal conductivity high tensile strength Ductile & malleable ZINC low hardness & Very corrosion resistant A relatively heavy metal, but lower density than cast iron, copper or lead relatively high fusibility but lower than that of lead LEAD High density Melts very easily Low tensile strength ALUMINIUM Low density Relatively low tensile strength

Adj VS Adv 1.- Such a concentration of lead is highly dangerous for men. 2.- Hard steel is generally preferred when building huge bridges. 3.- Magnesium is known as a metal which burns easily. 4.- The cable is to be covered by a thin rubber coating. 5.- Stainless steel consists of slightly high proportions of chromium. 6.- If you put a pipe here, it should not be easily bent./ 7.- This alloy performs well due to its exceptional electrical conductivity. 8.- Researchers found extremely rare compounds on Mars. 9.- Chalk is a good example of a soft material 10.- Protons are positively charged particles.

EXCERCISE: Comparison As copper has become RARER and MORE EXPENSIVE, aluminium has come into use even though it has a HIGHER resistance THAN copper. In early days, people thought that the electric current flowed in THE SAME way AS water In Volta's cell, one of the metals is chemically MORE ACTIVE THAN the other and gives off electrons which are attracted by THE LESS ACTIVE metal. If we let the bar cool FASTER than before, we obtain a metal which is HARDER and MORE EASILY machineable. Hydrogen is one of THE LIGHTEST elements while uranium is one of THE HEAVIEST. Electrons orbiting FARTHER from the nucleus are those which are MORE EASILY drawn away. In generators, THE FASTER the wires move, THE GREATER the generation of emf. Thermoplastics can be reheated AS MANY times AS required. MOST (OF THE) scientists use computers in their work. Oil is THE MOST WIDELY USED energy source There are .SO MANY materials that we can always find the appropriate one for our needs We spend SO MUCH energy in producing electricity that we should concentrate our efforts on other possibilities to generate it

EXERCISE: Comparison Cast iron is the least malleable of these metals. Similarly, high carbon steels are not very malleable with less carbon, steels become more malleable. Med. C steels are more malleable than H.C. steels. Low carbon steels have even more malleability. Wrought iron is the most malleable of these ferrous metals. Wrought iron is also the most elastic of these metals. L. C. steels are less elastic because they contain more carbon. Medium carbon steels are less elastic than low carbon steels. H. C. steels have less elasticity because they have more carbon Cast iron has much carbon in it and therefore it is the least elastic. The more C these contain, the less malleable and elastic they are. W iron contains very little/the least C and it is the most elastic. Cast iron contains more/the most carbon and it has the least elasticity.

EXERCISE: expressions If we...COMPARE.. wrought iron and cast iron, we may find some...SIMILARITIES.. Both of them are ..SIMILAR IN THAT....they contain iron; wrought iron, . LIKE/IN THE SAME WAY AS/SIMILARLY TO cast iron, HOWEVER..., .ALTHOUGH they are very....SIMILAR IN .... their composition, we may notice some ...DIFFERENCES... REGARDING/WITH RESPECT TO/ AS REGARDS their properties; thus ,wrought iron is very malleable, WHEREAS/WHILE cast iron is THE LEAST MALLEABLE of all ferrous metals .. ON THE OTHER HAND, cast iron ...DIFFERS FROM wrought iron in elasticity because WHEREAS/WHILE the former has a very poor elasticity, the latter is very elastic. The..DIFFERENCE between these two metals comes from the different amount of carbon content: THE HIGHER the content of carbon, THE LESS MALLEABLE AND ELASTIC these metals are.