CHEMISTRY OF NOBLE GAS

Created by:Ni Luh Gede Enik Karnila Yanti (1113031079)Ni Ketut Sepmiarni (1113031087)RKBI Class

CHEMISTRY EDUCATION DEPARTEMENTFACULTHY OF MATHEMATICS AND NATURAL SCIENCESGANESHA UNIVERSITY OF EDUCATIONSINGARAJA2012CHEMISTRY OF NOBLE GAS

Noble gases are a special group because it is the most stable group in the periodic table. Noble gases have electron valence configuration s2p6, except helium with electron valence configuration s2. This structure cause noble gases are unreactive. Although noble gases are stable and unreactive but, it could form compounds with some mechanisms. Beside that, noble gases are useful in human life. In this essay will explain briefly the properties of noble gases, their uses, as well as some compound of noble gases and their ways of preparation.In periodic table, group of VIIIA also called noble gases group. In one period, the noble gas has smallest atomic radii. The elements of the noble gas group are not very reactive because they are stable (have eight electrons in the valence shell). The noble gases are, in fact, comparatively unreactive, but some (especially xenon and krypton) are not inert even though that label was once applied to the noble gas. Elements belonging to noble gases are He, Ne, Ar, Kr, Xe, and Rn (James E. House, 2008). Some properties of noble gases can be seen in the following tablePropertyHeNeArKrXeRn

Atomic number21018365486

Atomic mass4.002620.18339.94883.80131.30222

Electron configurations1 s2[He] 2s2 2p6[Ne] 3s2 3p6[Ar] 3d10 4s2 4p6[Kr] 4d10 5s2 5p6[Xe] 4f14 5d10 6s2 6p6

Melting point (K)0.9524.583.78116.6161.3202

Boiling point (K)4.2227.187.29120.8166.1211

Ionization potential (kJ mol-1)237220811520135111701037

Atomic radius (0pm)122160191198218-220

Density (bg L-1)0.17850.9001.7843.735.889.73

Solubility in H20 (103 x Xc)7.128.7330.257.0105230

Abundance in nature (%)0,000520,00150,920,000110.00000870.0778613

Color of spectrumColorlessRed purpleVioletWeak violetBlue green Colorless

(James E. House, 2008) Elements belonging to noble gases are He, Ne, Ar, Kr, Xe, and Rn. First is helium (He), this element was named helium the Greek word helios, its mean sun. (James E. House, 2008). In 1968 Pierre Jansen found evidence of He during the total solar eclipse when he detected a new line in the solar spectrum. In 1895, Ramsay discovered He in the uranium mineral cleveite. At the same time, the Swedish chemists Cleve and Langlet discovered He in cleveite. In 1907 Rutherford and Royds demonstrated that alpha particles are He nuclei (Yulianto Mohsin, 2005). It has long been related to nuclear chemistry because of the formation of alpha particles ( 4He2+) during the decay of heavy nuclei (James E. House, 2008). Second is neon (Ne), in 1898 Ne was discovered by William Ramsay and Morris Travers. This element was named neon the Greek word neos, its mean new. In nature, it was produced by some of the stars from the nuclear reactions that occur in the star. Ne is naturally present in the form of isotopes. There are three stable isotopes of Ne are Ne-20, Ne-21 and Ne-22 (James E. House, 2008).. Third is argon (Ar), Ar was discovered in 1885 by Sir William Ramsay as a constituents in the residual gas after O2 and N2 were removed from air. The name comes from the Greek argos, which means inactive. Argon is generated by the electron capture decay of 40K (James E. House, 2008). Fourth is krypton (Kr) and xenon (Xe), in 1898 Ramsay and Travers discovered a new substance that is Kr and Xe. Kr and Xe were founded in the residue left after almost all of liquid air evaporating. This element was named Kr the Greek word kryptos, its mean hidden and Xe the Greek word xeneus its means stranger.The last is radon (Rn), in 1900 Rn was by discovered Friedrich Dorn, called emanation (emission) of radium. In 1908, Ramsay and Gray, named niton, isolate these elements and determine its density, and then it was known that this element is the heaviest gas of all the elements that have been found at that time. Rn is inert and occupies the last position in the group of noble gases in the periodic table. Rn was produced in the three naturally occurring decay series of 235U, 238U, 232Th. Each of that series consists of numerous steps before stable nuclide results, but the final product is Rn in each case. All of the isotopes are radioactive and decay by -emission to produce isotopes of polonium.All noble gases present in the atmosphere and used in human life. Here are the benefits of each element of the noble gas. He was used to fill the balloon, as a mixture of gas for sea dives in lieu of N2. He also used to substitute N2 as heliox gas mixture (He-O2) in vitro oxygen to divers, because it is unreactive, very light weight and solubility in body tissues less than N2. Liquid He was used for cooling the metal coil in the scanner, because a low boiling point. It was also used for heat transfer medium in nuclear reactors (Hari Prasetyo Widodo, 2011).Picture 1. The function of HeNeon was used as billboards and lights on the runway. Ne produces high-intensity light when an electric current pass. This light can be seen from a far and through the mist. Red is the characteristics color of Re. However, the use of fluorescent tubes with powder can produce other colors. Ne also used in TV tubes, gas lasers, high-voltage indicators and liquid it was used as a coolant.

Picture 2. The function of NeArgon was used in light bulbs replace the O2 because it is unreactive so that the filaments are not easily broken. The use of Ar enables heating the filament at a higher temperature thus obtained is more white light. Ar was used as an inert atmosphere in welding, metal production in industry and in laboratory experiments. This is because Ar was unreactive that metal will not oxidize as if the process takes place in the open air. Ar used for laser to produce a variety of light with blue-green waves. Lasers can be used for live entertainment and medical purposes, such as eye surgery and hardening dental fillings.

Picture 3. The function of ArKrypton (Kr) was used in light aircraft on the runway, the lighthouse, the light high-speed photography, fluorescence and laser for treating eye retina. Kr-85 is the isotope, Kr was used for industry to control the thickness of the paper industry, because it is radioactive, it can remove particles of (Beta).

Picture 4. The function of KrXenon (Xe) was used to flash (flash gun) and vacuum tubes. In a vacuum tube, it was produced a very bright white light. Xenon is the only noble gas that is anesthesia / drugged at atmospheric pressure. Xe was considered as an ideal anesthetic among other anesthetics. It was also use in nuclear reactor.

Picture 5. The function of XeRadon (Rn) was used for cancer therapy. Rn that is radioactive put in a small tube sealed and placed near the tissue affected by cancer. It also used for earthquake warning system. Rn comes from the decay of U and Ra in rocks. As the plates move, Rn levels will increase due to the release of Rn of rocks. Rn levels are an indicator of the earthquake. Picture 6. The function of RnThats all about the properties and function of noble gas elements. Although elements of the noble gas group are stable, there was a noble gas elements are capable forming compounds or bonded with other elements. For example compound that consists of xenon such as XeF2, XeF4, XeF6 and other noble gas chemistry such as KrF2.Linus Pauling (1933) speculated about the reaction of O2 with PF6 mentioned earlier suggested that a similar reaction with xenon might be successful in light of the similarity in ionization potentials. It should be apparent that if Xe is to react, it should be with an extremely strong oxidizing agent, and F2 is a suitable candidate. By this means, the difluoride and tetrafluoride of xenon were prepared as a mixture of the elements was heated or subjected to electromagnetic radiation. Xenon difluorides is made by interaction of Xe with a deficiency of F2 at high pressure. The deficiency of F2 insures exclusive formation of the difluoride. Xe(g) + F2(g) XeF2(s)It dissolves in water to give solutions with a pungent odor of XeF2. Hydrolysis is slow in acid solution, but rapid in the pressure of bases, due toXeF2 + 2 OH- Xe + O2 + 2 F- + H2OXenon tetrafluorides is easy to prepare. When preparing XeF4, a mixture containing a 5 : 1 ratio of fluorine to xenon was heated at 4000C and subjected to several atmospheres pressure about 6 atm.XeF2(g) + F2(g) XeF4(s)Xenon heksafluorides at a higher ratio of fluorine to xenon was used, XeF6 can be obtained. Xenon heksafluoride (XeF6) is obtained by the interaction of XeF4 and F2 at temperature above 2500C and pressure greater than 50 atm. XeF4(g) + F2(g) XeF6(s)Monomeric XeF6 in the liquid or the vapor has a distorted octahedral structure because of a lone of electrons at Xe.Reactions of Xenon Fluorides and Oxyfluorides, many of the reactions that xenon fluorides undergo are similar in some ways to those of interhalogens. However, the xenon halides differ markedly in terms of their reactivity with XeF2 being much less reactive than either XeF4 or XeF6. The difluoride reacts only slowly with water,2 XeF2(s) + 2 H2O(l) 2 Xe(g) + O2(g) + 4 HF(aq)But in basic solution a different reaction takes place rapidly, which can be shown as2 XeF2 + 4 OH- 2Xe + O2 + 2 H2O + 4 F-Xenon tetrafluoride reacts rapidly with water by undergoing disproportionation,6 XeF4 + 12 H2O 2 XeO3 + 4 Xe + 3 O2 + 24 HFAs xenon +4 is converted into xenon +6 and Xe. The oxide is an explosive compound that is also produced by the hydrolysis of XeF6.XeF6 + 3 H2O XeO3 + 6 HFXenon trioxide is formed in the hydrolysis of XeF4 and XeF6. The hydrolysis may take place by the formation of XeOF4 as an intermediate (Albert F Cotton, 1930).XeF6 + H2O XeOF4 + 2 HFXeOF4 + 2 H2O XeO3 + 4 HFSome oxides of xenon are known, and like most other compounds of xenon, they are usually obtained from the fluorides. The heat of formation of XeO3 is approximately + 400 kJ/mol so, it should be not surprise that the compound is a very sensitive material. On evaporation of water, XeO3 is obtained as a white deliquescent solid that is dangerously explosive. The structure of XeO3 can be shown as follows:

In the first structure showing only single bonds, the formal charge on Xe is +3 so contributions from structures showing double bonding are significant. In basic solution, a reaction between OH- and XeO3 occurs and xenate ion (HXeO4-) is formed, which can be shown asXeO3 + OH- HXeO4-A reaction of HXeO4- in basic solution is very similar, and it can be shown as2 HXeO4- + 2 OH- XeO64- + Xe + O2 + 2 H2OWhich result in the production of the perxenate ion, XeO64-. Several solids containing perxenate ion have been isolated, and the ion is the conjugated base of weak acid, H4XeO6. Therefore, the salts hydrolyze to produce basic solutions.XeO64- + H2O HXeO63- + OH-HXeO63- + H2O H2XeO62- + OH-With the oxidation state of Xe in perxenates being +8, they are as expected, very strong oxidizing agents. In an analogous reaction, xenon oxyfluorides are produced by the reactionsXeF6 + 2 XeO3 3 XeO2F22XeF6 + XeO3 3 XeOF4Krypton difluoride, as mentioned earlier krypton is known to form several compounds, but they are fewer and less well characterized than the compounds of xenon. The difluoride has been obtained by electric discharge through a mixture of Kr and F2 at low temperature. Krypton difluoride is obtained when an electric discharge is passed through a mixture of Kr and F2 at 1800C. As in the case of xenon difluoride, a cation is produced in the reaction with a strong Lewis acid such as SbF5.KrF2 + SbF5 KrF+SbF6-It resembles XeF2 being volatile white solid constructed of linear FKrF molecules, but differs in that it is thermodynamically unstable.KrF2(g) Kr(g) + F2(g) H0 = -63 kJ/molXeF2(g) Xe(g) + F2(g) H0 = 105 kJ/molKrypton difluoride has been prepared from the elements, but only at low temperature using electric discharge. When irradiated with ultraviolet light, a mixture of liquid krypton and fluorine reacts to produce KrF2.The chemistry of krypton is well estabilished, but is still much less extensive than that of xenon. Although a rather extensive chemistry of the noble gases has developed, the vast majority of the studies have dealt with the xenon compounds. As expected, radon difluoride can be obtained, but because all isotopes of radon undergo rapid decay, there is not much interest in the compound (James E. House, 2008).Based on explanation above, it can be conclude than noble gases are a special group because it is the most stable group in the periodic table. The elements of the noble gas group are not very reactive because they are stable (have eight electrons in the valence shell). Noble gas was useful in daily life such as in industry and health. Although it is stable and very unreactive noble gases could still form compounds with some mechanisms, for example the chemistry of xenon such as XeF2, XeF4, XeF6 and other noble gas chemistry such as KrF2.

References Cotton, F. Albert dkk. 1930. Basic Inorganic Chemistry. Canada: John Wiley & Sons, Inc.Cotton and Wilkinson. 1989. Kimia Anorganik Dasar. Jakarta: Universitas Indonesia.House, E James. 2008. Inorganic Chemistry. Canada: Academic Press.Siregar, Manimpan and Sudria. 1999. Kimia Anorganik I. Singaraja: Jurdik Kimia MIPA STKIP Singaraja.

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