Paper Noble Gases

Throughout the history of science, there have been thousands of new and revolutionary discoveries that have truly changed the way we look at the world. Not only have they resulted in advances in fields such as medicine and technology, but they have propelled scientists into a new world of understanding and innovative thought. Focusing on the noble gases in particular, it is evident that they have undergone a long history of observation and discovery ever since the late 1800's. Having been the main focus for many scientists, learning about the noble gases has allowed them to understand more about ionization energies and the tendencies for elements to react. Ultimately, the expanding knowledge of noble gases has lead to many discoveries of the different noble elements that exist as well as supporting many scientific rules and theories such as the octet rule.

The name "Noble Gas" was derived from the German noun Edelgas to indicate the relatively low level of reactivity of the elements. 1 Of the many scientists that were involved with such phenomena at the time, Pierre JanssenandJoseph Norman Lockyerwere among the first to discover a noble gas. 2 In 1868, as they were observing the sun, they noticed the characteristic spectral lines that had been obtained and noticed that they were unlike any other element they had seen. 3 As a result, they identified this new element as Helium, which comes from the Greek word Helios or sun. Following this discovery several decades later, in 1895, an English physicist by the name of Lord Rayleigh learned that the density of nitrogen gas obtained from the air was different from that of nitrogen obtained from various chemical reactions. 3 Concluding that the nitrogen gas in the air had to have been contaminated with another gas, he collaborated with Scottish chemist William Ramsay with the goal of identifying this unknown substance. As a result, Ramsay designed an experiment which passed nitrogen from the atmosphere over heated magnesium as a means of removing the nitrogen itself. The final product that Ramsay obtained turned out to be a non-reactive residual gas. Upon isolation and observation of its emissions spectrum through the use of a high-voltage electrical discharge, the substance was identified as a new element and was called Argon or lazy in Greek due to its lack of chemical reactivity and very stable nature. 3 During the time of this experimentation, Ramsay also worked with Swedish chemist Per Theodor Cleve, with whom he was able to isolate Helium in a mineral known as cleveite. This allowed him to complete further experiments with Helium, further supporting the conclusion that Helium was a noble gas. Upon completing these discoveries, Ramsay moved on to exploring even more noble gases through processes such as fractional distillation. 3 By separating mixtures into their component parts, liquid air being the primary example in Ramsay's experiments, he announced the discoveries of neon, krypton, and xenon in 1898. 5 Shortly after, radon was first identified in the same year by Friedrich Ernst Dorn. Initially known as "radium emanation" due to the fact that it was a gaseous decay product of radium, it was later called radon when it was officially regarded as a noble gas in 1904. 5 That same year, Ramsay and Rayleigh both received Nobel Prizes in the fields of chemistry and physics, respectively, for their outstanding discoveries of the noble gases.

Generally speaking, the elements were discovered as noble gases because they all maintained certain chemical characteristics that were unique from other elements. These characteristics provided the necessary groundwork to understand the behavior of the gases and are still used by scientists today. First, the elements all have rather high ionization energies. This means that a vast amount of energy is required to remove the outermost electron from their atoms. 7 Later incorporated into the Mendeleev's periodic table, these gases were placed to the far right due to the increasing ionization energies of elements from left to right. Additionally, they have very stable and closed shell electron configurations. As a result, they rarely lose valence electrons. Specifically, the shells containing valence electrons are completely filled. Consequently, the elements do not have the tendency to lose or gain any electrons since they have already fulfilled their goal of attaining a full outer shell of electrons.

This concept was first understood in the early 1900's when Gilbert N. Lewis formulated the octet rule. He claimed thatwhen atomscombine, their primary goal is to have eightelectronsin theirvalence shells, ultimately giving them the sameelectron configurationas the noble gases. 4 Not only does this result in more stability for the atoms, but it also causes them to be less reactive. The octet rule became the rationale behind many of the conclusions that were made in regards to an element's tendency to react with other elements. Relating this rule to the noble gases, it became evident that the primary reason why they do not frequently react with other elements is that their valence shells are filled. 6 Lewis' rule allowed scientists to attain a newer understanding of the reactivity levels of noble gases. He shifted the focus towards the valence electrons of the atom as being the primary determinant of reactivity in a chemical reaction.

However, the octet rule continued to aid chemists with many other discoveries and understandings of elemental behaviors. It helped chemists determine the placement of electrons throughout various electron orbitals in an atom. 4 Additionally, it allowed them to identify whether electrons have been added or lost throughout various chemical reactions. 4 By providing the primary concepts required to understand the reasoning behind chemical reactivity and electron involvement, the octet rule lead to the formation of Lewis structures. Also known as Lewis or electron dot diagrams, these depictions primarily represent the bonding that occurs between the atoms of a molecule and the total valence electrons that exist in the molecule. 3 And even today, the octet rule can be applied to the modern periodic table and the placement of elements. The elements that are on the left side of the periodic table tend to have fewer valence electrons and therefore lose them in chemical reactions giving them a positive ionic state. On the other hand, elements on the right side of the periodic table, excluding the noble gases, have greater valence electrons and therefore tend to receive electrons to achieve their goal of acquiring a full valence or outer shell.

Looking back at the extensive yet phenomenal history of noble gases, it is evident that their discoveries helped scientists unravel a new way of thinking. It allowed them further advance their understandings of the reactivity levels of elements while observing the reasoning behind it. Furthermore, it added credibility to rules such as Lewis' octet rule and the proper understanding of Lewis structures. But more importantly, the noble gases revolutionized the field of chemistry by being the first elements to have completely filled valence shells. Leading chemists on a journey filled with new and profound advancements, the discoveries of the noble gases truly impacted scientific thought in a manner that has undoubtedly transformed the understanding of chemistry.

Works Cited

  1. "Lehrbuch der anorganischen Chemie -- RENOUF 13 (320): 268 -- Science."Science/AAAS | Scientific research, news and career information. 2009. Web. 05 Oct. 2009. .
  2. "Edelgas - English translation - dictionary." language portal. 2009. Web. 05 Oct. 2009. .
  3. Ebbing, Darrell D., and Steven D. Gammon.General Chemistry. 9th ed. Boston: Houghton Mifflin Company, 2007. Print.
  4. "Chemical Properties of Noble Gases |" - Online Tutoring, Homework Help for Math, Science, English from Best Online Tutor. 2008. Web. 05 Oct. 2009. .
  5. "Discovery of Noble Gases |" - Online Tutoring, Homework Help for Math, Science, English from Best Online Tutor. 2009. Web. 05 Oct. 2009. .
  6. "P-Block Elements |" - Online Tutoring, Homework Help for Math, Science, English from Best Online Tutor. 2009. Web. 05 Oct. 2009. .
  7. "Ionization Energy."Shodor A National Resource for Computational Science Education. 2009. Web. 05 Oct. 2009. .

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