From Hydrogen to Tellurium - ARGON

Argon


Argon with the chemical symbol Ar is number 18. It is located on the periodic table in the third row of the right hand column underneath Helium and Neon. Like Helium and Neon, Argon is a member of the inert or noble gas family. This means that it is a gas at room temperature and that it is a very stable material that does not react with other elements, or itself for that matter.

Previously we have talked about the fact that air is a mixture of gases - mostly Nitrogen (78 parts of every 100) and oxygen (21 parts of every 100). Of the remaining 1 part a large amount of that is Argon.


At number 18, Argon has 2 electrons in its inner shell and 8 in each of the 2nd and 3rd shells. This means that all 3 electron shells are full. It is these full electron shells which make Argon so stable - it is neither looking for additional electrons to fill up the last few spaces nor looking to give away a few electrons to empty the outer shell.


The name Argon comes from the Greek word for lazy - very appropriate for an element which just won't react!


I was asked recently why the inner electron shell only has 2 electrons and the 2nd and 3rd 8. Well this is because in close to the nucleus the inner shell is very small and can only fit 2 electrons. The 2nd and 3rd shells are bigger and can fit 8 each. When we move on to the next row we will see that the 4th shell is considerably bigger and can fit an extra 10 electrons.


I was also asked about the position of the columns and the gaps in the first 3 rows. Well the elements are grouped in columns along with other elements with similar chemical behaviour. Helium behaves similarly to Neon and Argon so is placed in that group - it is in the group with full outer shells, not the group with 2 electrons in the outer shell.

So what is Argon used for? Well the main use is in situations when you want to prevent other reactions taking place so Argon is used for welding. It is also sometimes used as a preservative and also as a fire extinguisher.


Like Neon it becomes coloured when an electrical current is passed through it so it is used to make blue/purple advertising signs.