The Group I Elements Li, Na, K, Rb and Cs

The group I elements are all univalent, and have a remarkable affinity for oxygen; caesium and rubidium ignite spontaneously if placed in dry oxygen at room temperature. The chemical activity of the alkali metals appears to increase steadily in passing from lithium to caesium.

The metals are obtained by electrolysis of fused salts or salt mixtures. Because there is only one valence electron per metal atom, the binding energies in the close packed metal lattices¹ are relatively weak and the metals are consequently very soft and have low melting points.

Liquid alloys of alkali metals are known, the most important being the Na–K alloys. All of the alkali metals are highly electropositive and react with most other elements directly. The metals are found to dissolve in mercury to form amalgams. The group I metals are soluble in liquid ammonia to give solutions which are blue when dilute. They react directly with most non-metals to give one or more binary compounds. Owing to the highly electropositive character of the alkali metals the various oxides are readily hydrolyzed by water.

Примечание к тексту

1. close packed metal lattice – плотно упакованная решетка металлов

XII.Расскажите о свойствах щелочных металлов, пользуясь текстами 10 А и B.

LESSON 11

Грамматика. Инфинитив в функции определения.

Предтекстовые упражнения

I.Обратите внимание на инфинитив в функции определения в следующих предложениях и переведите предложения на русский язык:

1. This scientist was the first to point out the importance of the phenomena observed. 2. They are the last to leave the laboratory. 3. D. I. Mendeleyev was the first scientist to arrange the elements according to their atomic weights. 4. Water to be used for drinking should be thoroughly purified. 5. The action to follow the combination of equal volumes of hydrogen and chlorine in sunlight is known as explosion. 6. Gold was probably one of the first metals to attract the attention of man. 7. The best solvent to be employed for dissolving phosphorus is carbon disulphide. 8. Sodium peroxide mixed with cupric oxide to serve as a catalyst, reacts with water, liberating oxygen. 9. Oxygen has considerable ability to form double bonds. 10. The hardest substance to cut different materials with is diamond.

II.Переведите следующие предложения, обращая внимание на выделенные слова:

in spite of – несмотря на

In spite of the high boiling point mercury does show a small vapour presence at an ordinary temperature.

in terms of – на основании; исходя из; на языке; с точки зрения

A material system may be described in terms of the phases constituting it.

III.Прочитайте и переведите следующие слова без словаря:

mendelevium /ÇmendIÈlIvI«m/, function /ÈfÃNkSn/, thiosulphate /ÇTI«ÈsÃlfeIt/, ethylene /ÈeTIli:n/, classification /ÇklQsIfIÈkeISn/, vacant /ÈveIk«nt/, position /p«ÈzISn/, scandium /ÈskQndI«m/, gallium /ÈgQlI«m/, germanium /ÇdZÎ:ÈmeInI«m/, actinium /ÇQkÈtInI«m/

IV.Запомните чтение следующих слов:

contribution /ÇkntrIÈbju:Sn/, development /dIÈvel«pm«nt/, subsequent /ÈsÃbsIkw«nt/, arrangement /«ÈreIndZm«nt/, periodicity /ÇpI«rI«ÈdIsItI/, appreciate /«Èpri:SIeIt/, reverse /rIÈvÎ:s/, considerable /k«nÈsId«r«bl/, predict /prIÈdIkt/, comprehensive /ÇkmprIÈhensIv/, familiar /f«ÈmIlj«/, substantially /s«bÈstQnS«lI/, fluorine /ÈflU«ri:n/

TEXT 11 A

The Periodic Law

In spite of the importance of the earlier contributions, the major portion of credit¹ for the development of the periodic system must go to the Russian scientist, Dmitri Ivanovich Mendeleyev. The realization that the properties of the elements can be represented as periodic functions of their atomic weights made possible classification that has suffered few significant changes in the subsequent years.

It was in March of 1869 that D. I. Mendeleyev published his first account of the periodic system, in which he set forth the arrangement of the elements in terms of their increasing atomic weights. D. I. Mendeleyev was the first to fully appreciate the significance of this periodicity. In his first paper D. I. Mendeleyev pointed out the similarities of a number of properties of certain elements and reversed the order of atomic weights where necessary in order to maintain this group similarity.

Of considerable interest and importance is the fact that D. I. Mendeleyev left vacant positions in his proposed table for yet undiscovered elements and expressed the opinion that the chemical and physical properties of the elements to be discovered might well² be predicted from their positions in the table. In the summer of 1871 D. I. Mendeleyev published a more comprehensive treatment³ of what he called the Periodic Law. At this time he presented the more familiar form of the periodic table and although it differs somewhat from the one that is in use today, it is substantially the same. It was in his publication of 1871 that D. I. Mendeleyev utilized the periodic character to predict the properties of the elements to be described later as those of scandium, gallium and germanium. The remarkable agreement of the properties of these elements as described by D. I. Mendeleyev and those to be observed later is certainly a complete justification of D. I. Mendeleyev’s faith in his periodic law.

In December 1945 Glenn Seaberg made his first publication of a periodic table which depicted a new actinide series beginning with actinium. He said that American scientists were proud and happy to honour the name of D. I. Mendeleyev by calling element 101 “mendelevium”.

Примечания к тексту

1. the major portion of credit … must go – основная заслуга … принадлежит

2. well– зд. вполне

3. treatment – трактат

Запомните следующие слова:

account, agreement, appreciate, arrangement, comprehensive, considerable, depict, express, in spite of, justification, opinion, periodicity, predict, propose, remarkable, represent, set forth, significance, similarity, somewhat, substantially, subsequent, vacant

Упражнения

I. Определите функцию инфинитива в следующих предложениях и переведите предложения на русский язык:

1. If the filtrate contains elements to be determined it is usually necessary to reduce the volume by evaporation. 2. In quantitative analysis the element or radical to be determined is isolated in the form of a precipitate. 3. M. V. Lomonosov was the first scientist to find heat, light and electricity to be different forms of motion. 4. Sodium peroxide mixed with cupric oxide to serve as a catalyst reacts with water liberating oxygen. 5. The method of qualitative analysis to be employed depends somewhat on the nature of the substance to be analysed. 6. S. V. Lebedev was the first to study synthetic rubber-like compounds. 7. Metallic palladium has an unusual ability to absorb hydrogen. 8. M. V. Lomonosov was the first to give the definition of the second law of thermodynamics. 9. Atoms in the gas have the power to add an extra electron forming a negative ion such as I ˉ. 10. Urea was the first organic compound to be synthesized from inorganic materials. 11. Bertholet observed ethylene to dissolve in a solution of cuprous chlorine in dilute hydrochloric acid. 12. Various attempts have been made to interpret the absorption spectra of cupric amines. 13. Among the cuprous compounds no open-chain complexes joined through oxygen seem to be known. 14. The solubility of argentous acetate in water is found to increase on addition of alkaline or alkaline earth acetates.

II. Выпишите из текста предложения, содержащие эмфатическую конструкцию it is … that, и переведите их на русский язык.

III. Дайте прилагательные, соответствующие следующим существительным:

importance, scientist, significance, atom, periodicity, similarity, chemistry, physics, completion

IV. Переведите следующие слова как существительные и как глаголы:

change, increase, point, order, form, use

V. Переведите следующие предложения на русский язык, обращая внимание на выделенные слова:

1. In spite of the fact that compounds of fluorine had long been known, the element is so active that it was not obtained in appreciable quantities until 1886. 2. It is assumed that pure water is a non-conductor, in spite of the fact that perfectly non-conducting water has not yet been made. 3. We can explain reduction in terms of atomic structure. 4. Sometimes the data from which molecular weights are to be calculated are expressed in terms of the relative densities of gases.

VI. Ответьте на следующие вопросы:

1. Who contributed greatly to the development of the periodic system? 2. What did D. I. Mendeleyev realize? 3. When did D. I. Mendeleyev publish his first account of the periodic system? 4. What did he set forth in his account? 5. What did he point out? 6. What were vacant positions in the Table left for? 7. How many elements did D. I. Mendeleyev predict the properties of? 8. Why did American scientists call element 101 “mendelevium”?

VII. Прочитайте текст 11 B, не пользуясь словарем:

TEXT 11 B