Indicate the number of unpaired electrons is
`(i) P (ii) Si (iii) Cr (iv) Fe (v) Kr`.

Explanation

(a) `._(15)P = 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p_(x)^(1) 3p_(y)^(1) 3p_(z)^(1)`. No of unpaired electron = 3
(b) `._(14)Si = 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p_(x)^(1) 3p_(y)^(1) 3p_(y)^(1)`. No of unpaired electrons = 2
(c) `._(24)Cr = 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3d^(5) 4s^(1)`. No of unpaired electron = 6
(d) `._(26) Fe = 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6) 3d^(6) 4s^(2)`. No of unpaired electron = 4 (in 3 d)
(e) `._(36)Kr` = Nobles gas. All orbitals are filled. Unpaired electrons = 0