English for chemists

Section 11
Упр. 1. Прочтите заглавие текста 3 В, бегло просмотрите его и крат­ ко расскажите, о чем он.
Упр. 2. Назовите значения следующих интернациональных слов:
modem, form, systematic, inert, cube, formula, composition, horizontal, period, vertical, group

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Упр. 3. Определите значения выделенных слов по контексту.
1. The atomic numbers of helium and neon arc 2 and 10, those of lithium and sodium arc one greater (3 and 11). 2. The elements 3,11,19, 37, 55 and 87 arc very reactive chemically. 3. The sky in summer is often blue, but air is colourless. 4. The properties of the elements Li, Na, K, Rb, Cs and Fr resemble each other, and those of their compounds arc similar. 5. The horizontal rows of the periodic tabic arc callcd periods. 6. The seventh period on which the elements 106 and 107 have a hypothetical cxistcncc is callcd incomplete. 7. Chemists speak about the recurrence of properties, bccausc similar properties do occur again and again in every next period.
Слова к тексту:
cleavage — расщепление; congencr — принадлежащий к одному роду; arbitrary — произвольный, случайный; vary — изменяться; dependence— зависимость; connection — связь
Text 3 В
Прочтите текст про себя (контрольное время чтения — б минут).
The Periodic Table of the Elements
One of the most valuable parts of chcmical theory is the periodic law. In its modem form this law states simply that the properties of the chcmical elements arc not arbitrary, but depend upon the electronic structure of the atom and vary with the atomic number in a systematic way. The important point is that this dependence involves periodicity that shows itself in the periodic rccurrcncc of characteristic properties.
For example, the elements with atomic numbers 2,10,18,36,54, and 86 are all chemically inert gases. Similarly, the elements with atomic numbers one greater— namely 3,11,19,37,55, and 87 arc all light metals that arc very reactive chemically. These six metals — lithium (3), sodium (11), potassium (19), rubidium (37), cesium (55) and francium (87)— all rcact with chlorine and form colourless salts that crystallize in cubes and show a cubic cleavage. The chcmical formulas of these salts arc similar; LiCI, NaCl, KC1, RbCI, CsCl, and FrCl. The composition and properties of other compounds of these six metals are correspondingly similar, and different from those of other elements.
The horizontal rows of the periodic table arc callcd periods: they consist of a very short period (containing hydrogen and helium, atomic numbers 1 and 2), two short periods of 8 elements each, two long periods of 18 elements each, a very long period of 32 elements, and an incomplete period.
The vertical columns of the periodic table, with connections between the short and long periods as shown, arc the groups of chemical elements. Elements in the same group arc sometimes callcd congcncrs; these elements have closely related physical and chcmical properties.

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Упр. 4. Скажите, узнали ли вы что-нибудь новое из этого текста. Если да, то что именно?
Упр. 5. Разделите текст на тематические части и озаглавьте их.
Упр. б. Скажите, что говорится в тексте:
1) о строении периодической таблицы; 2) о периодах; 3) о группах элементов; 4) о том, как выявляется периодичность химических и фи­ зических свойств элементов.
Унр. 7. Найдите в тексте современную формулировку периодичес­ кого закона и переведите ее на русский язык.