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Calculate the screening constants of mem...

Calculate the screening constants of members of the `2nd` period for valency electrons.

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The correct Answer is:
`Li = 1.7,Be 2.05, B = 2.40, C = 2.75, N = 3.10, O = 3.45, F = 3.80, Ne = 4.15`
a. `Li(Z=3), 1s^(2) 2s^(1)`
`(sigma)_(2s^(1))=[(0.85xx "No, of electrons in" (n-1)th "shell"]`
`=0.85xx2=1.7`
b. `Be(Z=4)=1s^(2) 2s^(2)` (one electron is left in `2s` shell)
`(sigma)_(2s^(1))=[["("0.35 xx "No . of electrons left in the nth"],["shell i.e. in 2 s orbital"+"("0.85 xx"No . of"],["electron in (n-1)th shell"]]`
`=(0.35xx1)+(2xx0.85)=2.05`
c. `B(Z=5)=1s^(2) 2s^(2) 2p^(1)`
`(sigma)_(2p^(1))=[["("0.35xx "No. of electrons left in"],["nth shell"+"("0.85 xx "No. of electrons"],["in (n-1)th shell"]]`
`=(0.35xx2)+(0.85xx2)=2.40`
d. `C(Z=6)=1s^(2) 2s^(2) 2p^(2)` (one electron in `2p` and `2` electrons in `2s` are left)
`(sigma)_(2p^(1))=[["("0.35xx "No. of electrons left in nth shell +"],["("0.85 xx "No. of electrons in (n-1)th shell"]]`
`=(0.35xx3)+(0.85xx2)=2.75`
e. `N(Z=7)=1s^(2) 2s^(2) 2p^(3)` (two electrons in each `2p` and `2s` are left)
e. `N(Z = 7)=1s^(2) 2s^(2) 2p^(3)` (two electrons in each `2p` and `2s` are left)
`(sigma)_(2p^(2)) = [["("0.35 xx "No. of electrons left in nth shell+"],["(" 0.85 xx "No. of electrons in (n-1)th shell" ")"]]`
`= (0.35 xx 4)+(0.85 xx 2) = 3.10`
f. `O(Z=8) = 1s^(2) 2s^(2) 2p^(4)` (three electrons in `2p` and two electrons in `2s` are left).
`(sigma)_(2p^(3)) = [["("0.35 xx "No. of electrons left in nth shell+"],["(" 0.85 xx "No. of electrons in (n-1)th shell" ")"]]`
`= (0.35 xx 5)+(0.85 xx 2) = 3.45`
g. `F(Z = 9) = 1s^(2) 2s^(2) 2p^(5)` (four electrons in `2p` and two electrons in `2s` are left).
`(sigma)_(2p^(4)) = [["("0.35 xx "No. of electrons left in nth shell+"],["(" 0.85 xx "No. of electrons in (n-1)th shell" ")"]]`
`=(0.35 xx 3)+(0.85 xx 2) = 2.75`
h. `Ne(Z = 10) = 1s^(2) 2s^(2) 2p^(6)` (five electrons in `2p` and two electrons in `2s` are left).
`(sigma)_(2p^(5)) = [["("0.35 xx "No. of electrons left in nth shell+"],["(" 0.85 xx "No. of electrons in (n-1)th shell" ")"]]`
`= (0.35 xx 7) + (0.85 xx 2) = 4.15`
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