Why is oxygen a noble gas

Noble gases and noble gas configuration

The noble gases and the noble gas configuration are discussed in detail in this article. We will explain important properties of noble gases from a chemical point of view and their importance for our society today. This article belongs to the basics of chemistry.

This article is all about the chemical properties of noble gases. I will go into the important fundamentals of chemistry again in a moment, in order to clarify exactly these relationships. However, if you have any major gaps in your previous knowledge, I advise you to read the following articles first:


Noble gas properties

The elements of the 8. Main group of the periodic table (show periodic table in new window). These are the elements: helium, neon, argon, krypton, xenon, radon and ununoctium. Noble gases did not even appear on the very first periodic tables because they were only discovered shortly before 1900. All noble gases occur in the air.

The reason for the late discovery of the noble gases is due to one of their properties. Because noble gases hardly enter into chemical reactions. And since earlier scientists always tried to provide evidence of chemical reactions, they did not notice the noble gases. Proof was only possible through a precise analysis of the composition of air.

Since all noble gases have eight outer electrons, they are very stable. There is one exception, however: helium has only two electrons in the outer shell. Since the first shell can no longer accept electrons, the atom also has the highest possible number of outer electrons.


The noble gas configuration

The number of outer electrons just described represents practically the for atoms Optimal condition this one will too Noble gas configuration called. The reason for this is that this state is very favorable from an energetic point of view. The endeavor to strive for an energetically more favorable state can be listed as the main cause of chemical reactions.

When atoms strive to achieve the noble gas configuration, molecules and ions are often created. It should be noted, however, that there are also some chemical compounds in which not all atoms have the noble gas configuration, but which are still stable. And one more note, which, however, usually goes beyond school chemistry: Many ions or molecules are thermodynamically unstable in the state of the noble gas configuration.

Noble gases and their uses

I have just explained important properties of noble gases. In the following, the various noble gases will be briefly presented again.

  • helium: Helium has the atomic number 2 in the periodic table of the elements. The innermost electron shell is completely filled due to the two electrons. Helium has the lowest atomic mass and the lowest boiling point (-268.93 ° C). It also has the lowest density (0.1785 kg / m3) and the lowest water solubility. Helium is used in fluorescent tubes and mixtures of helium and oxygen help asthmatics to breathe.
  • neon: Neon has the atomic number 10 in the periodic table of the elements. Neon has a higher atomic mass than nitrogen and oxygen, but these only occur as molecules. This noble gas is known in particular from lighting technology. However, it is also used as a coolant in refrigeration technology
  • argon: Argon has the atomic number 18. Argon is the most common noble gas, has 1.784 kg / m3 at 273 K a density that is only slightly higher than that of nitrogen and oxygen. Argon is used in welding and in fire extinguishing systems.
  • krypton: Krypon has the atomic number 36. Krypton is part of our atmosphere. Because of the low concentration of approx. 1.1 ml / m3 the extraction of pure krypton is very complex. Krypon is heavier than air, non-flammable and colorless.
  • xenon: Xenon has the ordinal number 54. Xenon is one of the rarest elements on earth and over 3 times heavier than air. Due to its rarity, its price is very high and is only used when the lighter noble gases are not good enough. Most of it is used as a gas filling in light-generating lamps when a bright, white light is required.
  • radon: Radon has the atomic number 86. Radon is the heaviest elementary gas in the earth's atmosphere, all of its isotopes are radioactive. In medical radon balneology, radon is said to stimulate the human immune system and thereby alleviate diseases. From a scientific point of view, however, the positive effect of radon has not been proven.


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