Indicate the number of unpaired electrons in:
a. `P, b. Si, c. Cr`,
d. `Fe, e. Kr`

Explanation

a. `._(15)P=1s^(2)2s^(2)2p^(6)3s^(2)3p_(x)^(1)3p_(y)^(1)3p_(z)^(1)` Number of unpaired electron `=3`
b. `._(14)Si=1s^(2)2s^(2)2p^(6)3s^(2)3p_(x)^(1)3p_(y)^(1)` Number of unpaired electron `=2`
c. `._(24)Cr=1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(5)4s^(1)` Number of unpaired electron `=6`
d. `._(26)Fe=1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(6)4s^(2)` Number of unpaired electron `=4("in" 3d).`
e. `._(36)Kr=` Noble gas. All orbitals are filled. Unpaired electrons `=0`.