Instead of principle quantum number (n), azimuthal quantum number (L) &magnetic quantum number m,
a set of new quantum number s, t & u was introduce with similar logic but different value as defined
below
`s=1,2,3,...........oo` all positive integral values.
`t=(s^(2)-1^(1)),(s^(2)-2^(2)),(s^(2)-3^(3))`......... No negative value
`u=((t+1))/2"to"+((t+1))/2`(including zero , if any ) in integral step .
Each orbital can have maximum four electrons .
(s+t) rule is defined ,similar to `(n+l)` rule. The number of subshells in which the third shell is sub divided equal to
A. 1
B. 3
C. 5
D. 7
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Correct Answer - B
S=1
t=0
`u=-1/2,1/2`
No of subshell=1 , No of orbital=2
No of electrons =8
S=2
t=0,3
`u=-1/2,1/2`(for t=0)
u=-2,-1,0,+1,+2(for t=3)
No of subshell=2, No of orbital=7
No of electrons=28
S=3
t=0,5,8
`u=-1/2,1/2`(for t=0),
u= -3,-2,-1,0,1,2,3 (for t=5)
`u= -9/2, -7/2, -5/2, -3/2, -1/2, 1/2, 3/2, 5/2, 7/2, 9/2`(for t=8)
No of subshell=3, No of orbital=19
No of electrons =76
(1,0),(2,0),(3,0),(4,0),(2,3)....Energy order of (S,t)
For Atomic No. 24 (S+t) rule.
There is no electron in S=2,t=3