Question

Write electron configuration by using noble gas as a core for

I. Chromium [Cr, Z=24]

II. Cobalt [Co, Z=27]

III. Zinc(II) [Zn, Z=30

Answer 1

$1.Cr\Rightarrow 1s^2,2s^2,2p^6,3s^2,3p^6,3d^5,4s^1$

$2.Co\Rightarrow 1s^2,2s^2,2p^6,3s^2,3p^6,3d^7,4s^2$

$3.Zn\Rightarrow 1s^2,2s^2,2p^6,3s^2,3p^6,3d^{10},4s^2$