Here's why:
* Noble gases are located in Group 18 (VIIIa) of the periodic table. They are known for their stability and lack of reactivity.
* Valence electrons are the electrons in the outermost shell of an atom, which are involved in chemical bonding.
* The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable configuration of eight valence electrons, like that of the noble gases.
Exceptions:
* Helium (He), the first noble gas, has only 2 valence electrons. This is because its outermost shell is the first shell, which can only hold up to two electrons.
* The heavier noble gases (like radon) can sometimes have more than 8 valence electrons in certain situations.
However, the vast majority of noble gases have 8 valence electrons, making it the most common number.
