Question

Suppose bhat spin quantum number did not exist, such that only one electron could each orbital of a many electron atom. Give the atomic numbers of the first three noble gas atoms in this case.

Answer 1

$I)$ He have ${1s}^2$ configuration $\upharpoonleft \downharpoonright$

Therefore atomic number will be $1$ $\upharpoonleft$ (new)

$II)$ Ne have ${1s}^2{2s}^{2}2p^6$ configuration $\upharpoonleft \downharpoonright \upharpoonleft \downharpoonright \upharpoonleft \downharpoonright \upharpoonleft \downharpoonright \upharpoonleft \downharpoonright$

It's atomic number will be $5$ $\upharpoonleft \upharpoonleft \upharpoonleft \upharpoonleft \upharpoonleft$ (new)

$III)$ Ar have ${1s}^2{2s}^{2}2p^{6}3s^{2}3p^6$ configuration

It's atomic number will be $9$