Carmen discovered her passion for chemistry at a young age and continues to pursue chemistry. She also enjoys baking and writing essays.
Noble gases. What are they? Well, noble gases are a group of non-reactive elements, which are odorless and have no color, under specific conditions.  Helium, neon, argon, krypton, xenon, and radon are all noble gases. The reason why they don’t react to anything is because they have eight valence electrons, which makes them stable. However, helium is an exception, because it only has two valence electrons. It is still a noble gas.
Noble gas is translated from German and was first used by Hugo Erdmann in 1898. The German noun for noble gas was Edelgas.  In the periodic table, group 18 is the noble gases. All of the noble gases have a fragile interatomic force. They also all increase stably in atomic radius due to the raising number of electrons. Some noble gases amount on Earth depend on their atomic numbers. What does that mean? It means that the lower the atomic number is the more abundant it is. For example, helium is the most common noble gas due to its atomic number, which is only two. 
Noble gases also have relatively low boiling points and melting points. They are all also monatomic gases when they are under certain conditions such as certain pressure or temperatures. Melting and also boiling points will increase as you go down the periodic table.  The noble gases group were once thought to be part of group zero, due to the fact that they do not form compounds with other elements, because of their atoms. They were also believed to have a valence of zero. However, they soon discovered that the noble gases do indeed form some compounds with some other elements and have eight valence electrons. 
William Ramsay discovered most of noble gases. He discovered krypton, neon, and also xenon. Noble gases have very low boiling and melting points, which would make them very useful in refrigerants. They are also commonly used in lighting. That is because of their ability to not react to most chemicals. That makes noble gases perfect in lighting. 
Helium is one of the noble gases. It is number two in the periodic table, which means it has two protons and two electrons. Its symbol is He. Helium’s boiling and melting point is the lowest in all of the elements.  Helium is actually named after Helios, Greek god of the sun. That is because it was discovered on the sun.
Helium’s physical phase is a gas. Its melting point is 0.95 K and boiling point is 4.222 K. The first time helium was found was as a bright yellow color on the chromosome of the Sun. At first, it was considered to be sodium instead of helium.  Helium is commonly used in blimps, airships, and balloons due to the fact that helium is lighter than air, itself. Helium is completely safe for these applications, because it doesn’t burn or react to other chemicals (since it’s a noble gas).  A helium balloon would slowly deflate, because helium can leak or escape from balloons faster than carbon dioxide.
Hydrogen was used in blimps and balloons a long time ago. However, people started using helium instead due to helium’s capability to not catch fire or react to any other things.
Having ten protons and electrons, eight valence electrons, neon is the second noble gas. Its symbol is Ne. Neon was discovered in 1898. It was recognized as a new element, when it emitted a bright red spectrum.  It is also a very abundant element in the universe and solar system. However, it is rare on Earth. It forms no uncharged chemical compounds, because they are chemically immobile. Neon’s physical form is a gas and its melting point is 24.56 K. The boiling point of neon is 27.104 K. It is also considered the second lightest inert gas ever. Neon also has exactly three stable isotopes. 
It is commonly used and found in plasma tubes and refrigeration applications.  Neon was discovered by Sir William Ramsay and Morris Travers in 1852. The electron configuration for neon is [He] 2s22p6. 
Argon’s atomic number is eighteen and its symbol is Ar. It is the Earth’s third most common gas. It is common and mostly found in the Earth’s crust. The name “argon” came from a Greek word that means lazy or inactive. Therefore, referring to that argon does not react to anything. When argon is placed in a high voltage electric field, it would emit a purplish violet glow. It is mostly used in incandescent or fluorescent lighting. Argon’s melting point is 83.81 K and its boiling point is 87.302 K. 
Argon’s solubility is approximately the same as oxygen in water. Argon may be a noble gas; however, it can form some compounds. It can create argon fluorohydride, which is a mixed compound of argon, hydrogen, and fluorine. It’s stable that is below 17 K. Argon can be used in gas discharge tubes and it even produces a blue green gas laser. Also, argon can be founded in fluorescent glow starters. It was first discovered by Henry Cavendish in 1785. He suspected that argon was an air element. Argon was also the first noble gas discovered and until 1957 its chemical symbol was A. Scientists have now changed the symbol to be Ar. 
Sir William Ramasy discovered krypton, a gas, in 1898 in Britain. It has 36 protons and electron, which means its atomic number is thirty-six. Its symbol is Kr. Just like most other noble gases, it is used in lighting and photography.  Its name derived from the Greek word meaning the hidden one.
Krypton’s melting point is 115.78 K and its boiling point is 119.93 K. Krypton fluoride is commonly used as a laser, because it is very useful. Just like neon, it can also form some compounds. Krypton plasma is also used as a very powerful gas lasers. 
Xe is the chemical symbol for xenon. Fifty-four is its atomic number. It is, like all other noble gases, colorless and has no scent. Xenon can also undergo a few chemical reactions, such as becoming xenon hexafluoroplatinate. Xenon is especially used in flash lamps and other kinds of lamps.  It is also one of the few noble gases able to undergo a chemical reaction. Normally, they do not react to anything. Xenon has exactly eight stable isotopes.
Xenon’s original phase is gas. Its melting point is 161.40 K. Its boiling point 165.051 K. Xenon’s electronegativity is 2.6 on the Pauling scale.  Xenon is not so abundant which is due to the missing xenon problem. That is a theory scientists have come up with, because they believe that xenon may be trapped inside of minerals from inside the Earth, itself.
Radon is a radioactive noble gas. Its symbol is Rn and its atomic number is eighty-six. Meaning that radon has 86 protons and electrons. It is a product or result of natural decayed radium.  It is also one of the densest substances that stay in a gas form. Radon is considered as a health hazard, due to its radioactivity.
Radon’s melting point is 202 K and its boiling point is 211.5 K. It is also one of the densest element or gas at room temperature or just the densest in general. Radon also has no stable isotopes. 
Unnoctium is still being considered a noble gas or not. Its phase is a solid. Its symbol is Uuo and the atomic number is a hundred and eighteen. There is radioactive Unnoctium. It is very unstable and unsafe, just like radon. Its physical form is a solid. Its boiling point is 350±30 K. 
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Different Ways to Show an Atom
The Bohr Diagram
The Bohr Diagram is what scientists use to explain and show an atom’s subatomic particles. This technique was created by two scientists in 1913. They are: Niels Bohr and Ernest Rutherford.  This drawing is very simple and easy to do. The number of outer shells an atom has is the number of circles drawn. (Example on page 3). The atom, helium, has only 2 electrons, and assuming it is neutral, and 2 protons and neutrons. Therefore, 2 dots should be drawn on the line of the first circle, since only 2 electrons on the first outer shell. 4 more dots can be drawn within the circle to represent: 2 protons and 2 neutrons. However, there are some flaws to this method. First of all, this drawing does not display an atom correctly. The Bohr model shows an atom as flat, with electrons revolving around it. The electrons are in a perfect circular orbit. This is incorrect with real atoms. Real atoms do not have electrons orbiting around it in a circular motion. The electrons go all around the nucleus. They do not really go in a perfect circular pattern.
The Lewis Dot-Diagram
The Lewis dot-diagram is another way to explain an atom’s structure. More specifically, it represents the number of valence electrons an atom has. So, it only shows the last outer shell of an atom. The Lewis dot-diagram was created by Gilbert N. Lewis. In 1916, he showcased it in an article called The Atom and the Molecule.  For example, the nitrogen atom has 5 valence electrons, so this is what the Lewis dot-diagram would look like:
= a valence electron
Figure 5. A Lewis dot diagram of nitrogen.
Summary of the Diagrams
Ultimately, there are many different ways scientists use to represent and explain atoms. The Lewis diagram is extremely helpful when one wants to see what will happen if two atoms came together (the sharing of atoms). The Bohr diagram shows the whole structure of an atom. Ultimately, there are many different simple ways to explain what an atom is.
© 2018 Carmen Yang