Group 0, also known as noble gases, is a group of non-metal elements located on the far right column of the periodic table.
Mendeleev did not include the noble gases in the original periodic table because, at the time, most elements were discovered through reactions with known elements. However, since noble gases are the least reactive elements, they remained undiscovered.
Therefore, the noble gases were not discovered until after he had developed the table.
The table below shows the electronic configurations of the first three noble gases:
|Noble gas||Electronic structure|
Below is the structure of the atom of the first noble gas, which is helium.
The helium atom has two electrons in its first energy level, which can only hold a maximum of two electrons, making it full and stable. As a result, helium does not react chemically.
Below is the structure of Neon, which is the second noble gas.
Neon, the second noble gas, has 10 electrons in total. Out of these 10 electrons, 8 are located in the second energy level, which can hold a maximum of 8 electrons. This means that the outer shell of neon is full, making it stable and unreactive, just like helium.
All group 0 elements have boiling points lower than room temperature, which makes sense as they are called noble “gases”. However, as you move down the group, the boiling points increase due to the increase in the relative atomic mass. Among them, helium has the lowest boiling point at -269 ºC, while radon has the highest, at -60 ºC.
The reason for the increase in boiling point is related to atom size. Larger atoms have stronger intermolecular forces between them. This means that more energy is required to overcome these forces and convert the substance from a liquid to a gas.