Question

The third period contains only 8 elements even though the electronic capacity is 18 give scientific reason

Answer 1

Don't take 2n^2.
Take the subshell arrangement. According to subshell arrangements we have
3s, 3p
which means that third she'll has 2 + 6 = 8 electrons and we also see that third period has 8 electrons.
Thanks.

Answer 2

Answer:

• the third period contains only 8 elements even though the electrons capacity of the third sale is 18 due to the flow of electron octet.
• the octet rule reflect observation that atoms of the element of 3rd period and to combine in such a way that each atom has 8 electrons in its valence shell ,giving the same electronic configuration as noble gas..
• in short we can say that the outermost orbit can only pull up to 8 electron.