Read the text again and fill in the gaps with a suitable word from the boxes in each part.

A. ___________________

properties elements opaque chemical Periodic rust conducts materials

This (1) __________ element is a good conductor of both electricity and heat. In chemistry, this (Ancient Greek métallon, μέταλλον) is an element or alloy that (2) __________ electricity. In this element, atoms readily lose electrons to form positive ions. Those ions are surrounded by delocalized electrons, which are responsible for the conductivity.

Metals occupy most of the periodic table, while non-metallic (3) __________ can only be found on the right-hand-side of the (4) __________ Table of the Elements. A diagonal line drawn from boron (B) to polonium (Po) separates the metals from the non-metals. Most elements on this line are metalloids, sometimes called semiconductors. This is due to the fact that these elements have electrical (5) __________ common to both conductors and insulators (elements that don’t carry electricity). Elements to the lower left of this division line are called metals, while elements to the upper right of the division line are called (6)__________ .

Metals are very corrosive – they (7) __________ in contact with water. Painting (or any other form of covering) is a good way to prevent their corrosion.

Metals in general have high electrical conductivity, the ability to be deformed under stress. Optically speaking, metals are (8) __________ (that means ‘not clear’), shiny and lustrous. The large number of free electrons in any typical metallic element or alloy is responsible for the fact that they can never be categorized as transparent (9) __________ .

B. ____________________

properties use metals element harder oxygen rust

This is a metallic chemical (10) __________ with the symbol Fe (Latin: ferrum) and atomic number 26. It is a group 8 and period 4 element of the Periodic Table of the Elements and is therefore classified as a transition metal. This element and its alloys (steels) are the most common metals and the most common ferromagnetic materials in everyday (11) __________ . Pure iron is a metal but is rarely found in this form on the surface of the earth because it oxidizes in the presence of (12) __________ and moisture. Fresh iron surfaces are silvery-grey in color, but oxidize in air to form a red or brown coating of ferric oxide or (13) __________. Pure single crystals of iron are soft (softer than aluminium). The (14) __________ of iron can be modified by alloying it with various other (15) __________ to form steels. Alloying iron with appropriate small amounts (up to a few per cent) of other metals produces steel, which can be 1,000 times (16) __________ than pure iron. Iron is a necessary element used by almost all living organisms.

C. ___________________

characteristics alloys proportion practical alloys elements provide harder electrical

This is a mixture of two or more (17) __________ in which the major component is a metal. Most pure metals are too soft or chemically reactive for (18) __________ use. Combining different ratios of metals as alloys modifies the properties of pure metals to produce desirable (19) __________ . The aim of making alloys is generally to make them less brittle, (20) __________ , resistant to corrosion, or have a more desirable colour. Of all the metallic (21) __________ in use today, the alloys of iron (steel, stainless steel, cast iron, tool steel, alloy steel) make up the largest (22) __________ both by quantity and commercial value. Iron alloyed with various proportions of carbon gives low, mid and high carbon steels. The addition of silicon will produce cast irons.

Other significant metallic alloys are those of aluminium, titanium, copper and magnesium. Copper alloys have been known since prehistory—bronze gave the Bronze Age its name—and have many applications today, most importantly in (23) __________ wiring. The (24) __________ of the other three metals have been developed relatively recently; due to their chemical reactivity they require electrolytic extraction processes. The alloys of aluminium, titanium and magnesium are valued for their high strength-to-weight ratios; magnesium can also (25) __________ electromagnetic protection. These materials are ideal for situations where high strength-to-weight ratio is more important than material cost, such as in aerospace and some automotive applications.

Alloys specially designed for highly-demanding applications, such as jet engines, may contain more than ten elements.

D. ____________________

copper properties colour shape decoration 16th brass properties instruments mirror

This is an alloy of copper and zinc. The proportions of zinc and copper can be varied; this creates a range of brasses with various (26) __________ . In comparison, bronze is principally an alloy of copper and tin. Brass is a substitutional alloy. It is used for (27) __________ for its bright gold-like appearance; for applications where low friction is required such as locks, gears, bearings, doorknobs, ammunition, and valves; for plumbing and electrical applications; and extensively in musical (28) __________ such as horns and bells for its acoustic (29) __________ . It is also used in zippers. Because it is softer than most other metals in general use, brass is often used in situations where it is important that sparks not be struck, as in fittings and tools around explosive gases.

Brass has a yellow (30) __________ , somewhat similar to gold. It is relatively resistant to tarnishing, and is often used as decoration and for coins. In antiquity, polished brass was often used as a (31) __________ .

Forms of brass have been in use since prehistory. But the direct alloying of (32) __________ and zinc metal was introduced to Europe in the (33) __________ century.

Brass has good malleability (it means it is easy to shape) and acoustic properties, as it was mentioned above. It is used in many musical instruments, such as trombone, tuba, trumpet, cornet, euphonium, tenor horn, and the French horn. Even though the saxophone is classified as a woodwind instrument and the harmonica is a free reed aerophone, both are also often made from brass. In organ pipes of the reed family, brass strips (called tongues) are used as the reeds, which beat against the shallot (or beat "through" the shallot in the case of a "free" reed).

Brass has higher malleability than copper or zinc. The relatively low melting point of brass (900 to 940°C, depending on composition) and its flow characteristics make it a relatively easy material to (34) __________ . By varying the proportions of copper and zinc, the properties of the (35) __________ can be changed, allowing hard and soft brasses.

Today almost 90% of all brass alloys are recycled.

Aluminium makes brass stronger and more corrosion resistant. Aluminium also causes a highly beneficial hard layer of aluminium oxide (Al₂O₃) to be formed on the surface that is thin, transparent and self healing. Tin has a similar effect and finds its use especially in sea water applications (naval brasses). Combinations of iron, aluminium, silicon and manganese make brass wear and tear resistant.

E. ____________________

properties Diamond characteristics industrial electrical tools natural

This (from the ancient Greek αδάμας – adámas "unbreakable") is an allotrope of carbon. It is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions. (36) __________ has the highest hardness and thermal conductivity of any bulk material. Those properties determine the major (37) __________ application of diamond in cutting and polishing (38) __________ .

This material has remarkable optical (39) __________ . Combined with wide transparency, this results in the clear, colorless appearance of most natural diamonds. Diamond also has relatively high optical dispersion, that is ability to disperse light of different colors, which results in its characteristic luster. Excellent optical and mechanical (40) __________ , combined with efficient marketing, make diamond the most popular gemstone.

Diamond is the hardest (41) __________ material known, where hardness is defined as resistance to scratching and is graded between 1 (softest) and 10 (hardest) using the Mohs scale of mineral hardness. Diamond has a hardness of 10 (hardest) on this scale. Diamond's hardness has been known since antiquity, and is the source of its name. Diamond hardness depends on its purity.

Other specialized applications also exist or are being developed, including use as semiconductors: some blue diamonds are natural semiconductors, in contrast to most diamonds, which are excellent (42) __________ insulators.

F. ____________________

production non-hydraulic mixed important building join construction

This is a substance which can be (43) __________ with water and become hard after drying. The term ‘cement’ refers only to the dry powder substance. After the addition of water the cement mixture is referred to as ‘concrete’. Cement (mixed with water) can (44) __________ other materials together.

The word ‘cement’ traces to the Romans, who used the term "opus caementicium" to describe (45) __________ which was made from crushed rock with burnt lime as binder. Cements used in construction are characterized as hydraulic or (46) __________.

The most (47) __________ use of cement is the (48) __________ of a strong (49) __________ material.

G. ____________________

optical windows breaks industry laboratory important suitable

This is an amorphous (non-crystalline) solid material. It (50) _________ easily, and often optically transparent (or clear). It is commonly used for (51) __________ , bottles, modern hard drives, eyewear, etc. The word ‘glass’ developed in the late Roman Empire. It was in the Roman glassmaking center at Trier (now it is in modern Germany), that the late-Latin word glesum reffered to a transparent substance. Glass plays an (52) __________ role in science and (53) __________ . The (54) __________ and physical properties of glass make it (55) __________ for applications such as flat glass, container glass, optics and optoelectronics material, (56) __________ equipment, etc.

H. ____________________

process plastic improve classifications London products chemical

It is the general common term for a wide range of synthetic or semisynthetic organic amorphous solid materials used in the manufacture of industrial (57) __________ . This material is typically a polymer of high molecular mass, and may contain other substances to (58) __________ production, the quality of products and/or reduce costs. Monomers of Plastic are either natural or synthetic organic compounds.

The word is derived from the Greek πλαστικός (plastikos) meaning ‘suitable for moulding’, and πλαστός (plastos) meaning ‘moulded’. The first human-made (59) __________ was invented by Alexander Parkes in 1855; he called this plastic Parkesine (later called celluloid). It was demonstrated at the 1862 Great International Exhibition in (60) __________.

The common word ‘plastic’(as a noun) should not be confused with the technical adjective ‘plastic’, which is applied to any material which undergoes a permanent change of shape (plastic deformation) when strained beyond a certain point. Aluminium, for instance, is plastic in this sense, but not a plastic in the common sense; in contrast, in their finished forms, some plastics will break before deforming and therefore are not plastic in the technical sense.

Plastics can be classified by (61) __________ structure. Some important groups in these (62) __________ are the acrylics, polyesters, silicones, polyurethanes, and halogenated plastics. Plastics can also be classified by the chemical (63) __________ used in their synthesis, such as condensation, polyaddition, and cross-linking.

glass traditional properties shape classified rust bottles manufacturing

Other classifications are based on qualities that are relevant for (64) __________ or product design. Examples of such classes are the thermoplastic and thermoset, elastomer, structural, biodegradable, and electrically conductive. Plastics can also be (65) __________ by various physical (66) __________ , such as density, tensile strength, glass transition temperature, and resistance to various chemical products.

Plastics show good plasticity during manufacture; that allows them to be pressed, or shaped into a variety of forms — such as films, fibers, plates, tubes, (67) __________ , boxes, and much more. Plastic has relatively low cost; it is easy to (68) __________ ; it doesn’t (69) __________ in contact with water. That is why plastics are used in different products - from paper clips to spaceships. They have already displaced many (70) __________ materials, such as wood, stone, horn and bone, leather, paper, metal, (71) __________ and ceramic (in most of their former uses). But plastics are still too expensive to replace items like ordinary buildings, bridges, dams, pavement, and railroad ties.

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PROPERTIES OF MATERIALS	\|	Make a summary of this text. (List the materials mentioned and their main properties).

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