52. NCERT Exemplar XXIII

 

Hence, electron distribution = ($2, 8, 1$)($2, 8$)($2, 8, 2$)

$Na - 1e^-→Na^+$

$Na^+$ = $11$ $10$ $12$  electrons

Hence, electron distribution = ($2, 8, 1$)($2, 8, 2$)($2, 8$)

The atomic number of an element is equal to the number of protonsneutronselectrons in its atom. Since sodium atom and sodium ion contain the same number of protonsneutronselectrons, the atomic number of both is $10$ $11$ $12$ .