Question

General configuration of outermost and penultimate shell is $(n-1)s^2(n-1)p^6(n-1)d^{x}n{s}^2$. If n = 4 and x = 5 then number of protons in the nucleus will be

Answer 1

Given n = 4 and x = 5
$\Rightarrow (4-1)s^2(4-1)p^6(4-1)d^{5}4s^2$
$3s^{2}3p^{6}3d^{5}4s^2$ $Totalelectrons=2+6+5+2=15$
Electrons in first two orbits = 2 + 8 = 10
Hence, total electrons = 15 + 10 = 25
Number of electrons = number of protons = 25