Санкт-петербургского государственного университета высшее профессиональное образование т. А. Степанова, И. Ю. Ступина
party, property, speciality, purity, beauty
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1stepanova t a english for chemists
party, property, speciality, purity, beauty основа слова + -fy [fai] - » глагол verify, testify, intensify, signify, identify, simplify Ex. 4. Find the meaning of the following words in a dictionary. If you can't find the word, try to find its constituent parts and deduce the meaning of the whole word. hexagonal, widespread, well-formed, right-handed, left-handed, tetrahedron, test-tube, cross-road, test-paper, fcllow-studcnt, water-proof, shop-assistant Ex. 5. Find the meaning of the italicized words in a dictionary and translate the sentences into Russian. 1. Quartz occurs in many deposits as well-formed crystals. 2. It also occurs as a crystalline constituent of many rocks. 3. The crystals of quartz are left-handed or right-handed by their face development. 4. Silicic acid has the property of undergoing condensation very radily with elimination of water. 5. Each silicon atom is surrounded by four oxygen atoms. 6 . The structure o f quartz accounts fo r the hardness of the mineral. Text 7 A Silicon Dioxide Silicon is, next to oxygen, the most abundant element in the earth’s crust which occurs mostly in the form of oxides. Silicon dioxide (silica), Si02, occurs in nature in three different crystal forms: as the minerals quartz (hexagonal), cristobalite (cubic), and tridymitc (hexagonal). Quartz is the most widespread o f these minerals; it occurs in many deposits as well-formed crystals, and also as a crystalline constituent of many rocks, such as granite. It is a hard, colourless substancc. Its crystals arc identified as right-handed or left-handed by their face development 49 and also by (he direction in which they rotate the plane o f polarization of polarized light. The structure of quartz is closely related to that of silicic acid, H 4 Si04. In this acid silicon has ligancy 4, and is surrounded by a tetrahedron or four oxygen atoms, with one hydrogen atom attached to each oxygen atom. Silicic acid, which is a very weak acid, has the property of undergoing condensation very readily, with elimination of water. If each of the four hydroxyl groups of a silicic acid molcculc condenses with a similar hydroxyl group of an adjacent molcculc, eliminating water, a structure is obtained in which the silicon atom is bonded to four surrounding silicon atoms by silicon-oxygcn-silicon bonds. This proccss leads to a condensation product with formula Si02, sincc each silicon atom is surrounded by four oxygen atoms, and each oxygen atom serves as a neighbour to two silicon atoms. The structure of quartz and of the other forms of silica is described as consisting of Si0 4 tetrahedra, and each oxygen atom is a comer of two o f these tetrahedra. In order to break a crystal of quartz it is necessary to break some silicon-oxygcn bonds. In this way the structure of quartz accounts for the hardness of the mineral. Cristobalitc and tridymitc arc similarly made from Si0 4 tetrahedra fused together by sharing oxygen atoms, with, however, different arrangements o f the tetrahedra in space from that of quartz. Tridymitc resembles ordinary icc in structure, with silicon atoms in the oxygcn-atom positions; cristobalitc similarly resembles cubic icc. Words and Word-Combinations to Be Memorized account for, adjacent, arrangement, attach, closely, crystalline, deposit, dioxide, formula, fuse, granite, group, hydroxyl, identify, mostly, neighbour, position, quartz, be related to, serve, share, silicon, similarly, since, space, surround, together, undergo, weak Ex. 6. Give the Russian equivalents for the following: next to oxygen, mostly, the most widespread mineral, deposit, a well- formed crystal, constituent, a hard substancc, identify something, right- handed, left-handed, rotate, the plane of polarization, polarized light, be closely related to, be surrounded by, a weak acid, undergo condensation, a hydroxyl group, an adjaccnt molecule, be bonded to, lead to, condensation product, neighbour, in order to break a crystal, account for, be fused together, share oxygen atoms, ordinary icc, resemble smth. in structure Ex. 7. Give the English equivalents for the following: диоксид кремния, встречаться в природе, вращать плоскость по ляризации, структура кварца, быть тесно связанным с, окружать, при соединить к атому, очень слабая кислота, подвергаться конденса ции, очень легко, каждая из гидроксильных групп, молекула кислоты, связь, вести к, продукт конденсации, разорвать связь, таким образом, 50 объяснять, твердость минерала, делить между собой атомы кислоро да, различные расположения в пространстве, быть похожим на лсд по структуре Ex. 8. Fill in the blanks with prepositions where necessary. жүктеу/скачать 5,96 Mb. Достарыңызбен бөлісу:
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