Question

Why are there only 8 electrons in the outer shell?

Answer 1

1. The elements are bonded together by loss or gain of electrons, or by mutual sharing of electrons.
2. The valence shell plays a major role in the bond formation because the electrons are lost or gained through this shell only.
3. Every element wants to complete its outer shell electrons.
4. As per the octet rule, every element wants to complete its valence shell electron by accepting or donating the electrons.
5. Example: Sodium, the atomic number of Sodium is $11.$
6. The electronic configuration of Sodium is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1$, by losing one of its electrons it became stable.
7. Thus, it contains 8 electrons in its outermost shell.