What is the maximum number of electrons in the outermost shell of an atom ?

Explanation

The maximum number of electrons that can be accomodated in a shell depends on the formula `2n^2`, where .n. is the number of the given shell from the nucleus.
For example :
`K-" shell " - 2 xx(1)^2 = 2`, hence the first period has 2 electrons
`L-" shell " - 2xx (2)^2 = 8`, hence the second period has 8-elements.
`M-shell - 2 xx(3)^2 = 18`, but the outermost shell can have only 8 electrons, so the third period also has only 8 elements.