NeHeArKrXeRnOgAtomic structure
Apart from a helium (He)
atom that has two electrons
in its outer shell, all other
elements in this group have
atoms with eight electrons.Physical properties
All the members of this group
are colourless gases. Going
down the group, the density
increases – radon (Rn) is 54
times denser than helium.Chemical properties
Noble gases never react in
nature. In the laboratory,
heavier noble gases
can be forced to form
compounds with fluorine (F).Noble Gases
The group on the far right of the periodic table belongs to the noble gases.
These elements are described as “noble” because they do not react with
the other “common” elements, such as oxygen (O). Their atoms never
form bonds in nature, not even with atoms of their own kind, and so
they are always gases at room temperature.
Compounds
These gases form no natural
compounds. However, xenon
(Xe), krypton (Kr), and argon
(Ar) can be made to
form compounds.188-189_Noble_Gases_Opener.indd 189 02/12/16 6:52 pm