Part 19
Text 19
Rubidium and Cesium
(Continued)
Chemical properties
In their chemical reactions, rubidium and cesium are very similar to potassium. Both metals react very vigorously with air and water and must be protected from exposure to them.
Cesium hydroxide is the strongest base known and must be stored in silver or platinum out of contact with air because of its reactively with glass and CO2. Rubidium hydroxide is a powerful base as well.
Rubidium and cesium are known to form alloys with the alkali metals, mercury, antimony, bismuth, and gold. When alloyed with the last three metals, rubidium and cesium have the properties of the releasing electrons under the influence of light and can be employed in photoelectric tubes.
Applications
The present industrial applications of rubidium and cesium are limited and include use as getters in vacuum tubes, as photoelectric cell components and space missiles in ion propulsion engines, the latter being based upon the acceleration of ions and their discharge into space to provide the push for rockets. Since rubidium and cesium are easily ionized at rather low temperature, they offer great potential for this purpose.
The mass of cesium ions being greater than that of ions of lighter elements gives cesium an advantage. It is anticipated that the ion engine would be used to move vehicles through space once they are in orbit and that a nuclear power plant would provide the energy to run the engine.
One form which a thermoelectric generator using Rb or Cs can take utilizes the magnetohydrodynamic (MHD) principle. Cesium ions formed by heat are passed at a very high temperature through a magnetic field, and since they form an electrical conductor, they act like an armature of a conventional generator and cause electricity to be generated.
Cesium and rubidium are of importance because cesium , followed by rubidium is the most easily ionized element.
One believes, that production will rise to meet the demands1 at lower cost for rubidium and cesium.
Notes
1. To meet the demands: ®Ó lµm tho¶ m•n ®ßi hái
Exercises
I. Answer the following question:
1. What group of the periodic table do rubidium and cesium belong to?
2. What are the chemical properties of these elements?
3. Do rubidium and cesium form complex salts?
4. When do rubidium and cesium possess the property of releasing electrons?
5. Do you know any methods for preparing elemental rubidium and cesium?
6. Where are rubidium and cesium applied?
II. Give a summary of the texts Nos. 18 and 19
III. Translate the following sentences paying the attention to the bold type:
1. Cesium and rubidium are of importance because cesium followed by rubidium is the most easily ionized element.
2. The oxidation of titanium follows the parabolic rate law with time* at any given temperature.
* the parabolic rate law with time: phô thuéc víi thêi gian theo ®êng parabol
3. Cesium hydroxide must be stored in silver or platinum out of contact with air because of its reactively with glass and CO2.
4. Since cesium ions form an electrical conductor, they act like an armature of a conventional generator and cause electricity to be generated.
5. Cesium like lithium forms alkyl and aryl compounds of a wide variety
6. The needlelike crystals of potassium floutantalate X2 Ta E7, precipitate on cooling.
7. Zirconium nitride is such a stable compound that it is very unlikely that it can be used directly as a source of a metal.
8. It is anticipated that the ion engine would be used to move vehicles through space once they are in orbit.
IV. Translate the following sentences paying attention to complex Subject:
1. Rubidium and cesium are known to form alloys with the alkali metals.
2. In general, all tellurium deposits may be said to be gold bearing.
3. The action of flourine on thalium was found to be so vigorous that the metal became incandescent.
4. Klaproth was considered to have been the discoverer of the element uranium.
5. The stability of thorium metal with respect to oxidation in air appears to be a function of the oxide content of the metal.
V. Translate the following sentences paying attention to complex Object:
1. We know transistors to be used as amplifiers and in place of conventional vacuum tubes.
2. Specialists connsider cast cobalt to have a tensile strength of 35.000 psi.
3. Exeriments showed gallium to have been recovered from sodium aluminate liquor by the Bayer process.
4. The iron- cobalt equilibrium diagram shows cobalt to be entirely miscible with gamma iron.
5. John demonstrated uranium to deform commonly by twinning.
VI. Translate the following sentences paying attention to the Participle:
1. Rubidium and cesium are used as getters in vacuum tubes and for space missiles in ion propulsion engines, the latter being based upon the acceleration of ions.
2. If alloyed with antimony, bismuth and gold, rubidium and cesium have the property of releasing electons under the influence of light.
3. When handling thallium a person must be protected against its poisonous effects.
4. Transistors are being produced on a pilot plant scale.
5. Being one of the transition elements, titanium has a high modulus of elasticity to density ratio and a high melting point.
6. Selenites being formed by neutralizing selenous acid with hydroxides and carbonates are poisonous.
VII. Translate the following sentences paying attention to the word in bold type:
1. It is known that the present industrial applications of rubidium and cesium are limited.
2. The mass of cesium ions being greater than that of ions of lighter elemets gives cesium an advantage.
3. The compounds of tellurium resemble those of selenium.
4. One believes that production of rubidium and cesium will rise to meet the demands at lower cost for these elements.
5. Fluorine forms strong hydrogen bonds, oxygen weaker ones.
VIII. Translate into English:
1. Nh ®• biÕt, rubidi vµ cesi rÊt gièng kali trong c¸c ph¶n øng ho¸ häc.
2. C¸c thÝ nghiÖm ®• chØ ra r»ng, ph¶n øng gi÷a cesi vµ níc kÌm theo tiÕng næ.
3. Cesi peoxit lµ mét baz¬ rÊt m¹nh nªn cÇn ph¶i b¶o qu¶n nã trong chai b¹c hoÆc chai platin vµ c¸ch ly khái sù tiÕp xóc víi kh«ng khÝ.
4. Ngêi ta thÊy r»ng, rubidi vµ cesi t¹o thµnh c¸c hîp kim kh«ng nh÷ng víi kim lo¹i kiÒm mµ cßn víi mét sè kim lo¹i kiÒm thæ.
5. Sau nhiÒu nghiªn cøu ®Çy ®ñ cña c¸c nhµ khoa häc ngêi ta thÊy r»ng rubidi vµ cesi ®îc sö dông réng r•i trong tªn löa vµ vò trô.
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