Question

How many valence electrons are in $ X{{e}^{2+}}$ ?

Answer 1

Hint To solve this question first we have to understand the meaning of the term orbital. Orbitals refers to the dimensional motion of an electron around the nucleus in 3-D motion. The number of orbitals can be determined using the electronic configuration. Electronic configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbital.

Complete step by step solution:
According to the octet configuration as the name suggests Oct means eight the atom has eight electrons in the outermost orbit. Valence shell is the outermost shell of every element and valence electrons are the number of electrons which are present in the valence shell of the electrons. To have an inert configuration, an element must follow the octet rule. There are some exceptions to it.
Atomic number of xenon= 54
Electronic configuration of xenon =$ [Kr]4{{d}^{10}}5{{s}^{2}}5{{p}^{6}}$
The number of electrons present in the valence shell =8
Now Xe has +2 charge it means that it loses two electrons, hence the valence electrons is 6.

Additional information:
limitations of octet rule:
As hydrogen and helium both have only one and two electrons respectively in their outermost shell it is impossible for them to have eight electrons in their outermost shell. So there are many compounds which have less than eight electrons in their outermost shell but are still stable.
Similarly, there are many compounds which have more than eight electrons in their outermost shell but are still stable.

Note: The octet rule is based on the concept that electronic configuration of the noble gases is most stable and they have eight electrons in their outermost orbital so every element should attain the similar electronic configuration to become stable.