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Here for K-Shell, corresponding to Principal Q.N. n=1, l can be only 0.There is only s-subshell.
For L- Shell, corresponding to Principal Q.N. n=2, l can be 0 and 1.Here there are two subshells namely: s-subshell and p-subshell.
For M- Shell, corresponding to Principal Q.N. n=3, l can be 0 ,1and 2. Here there are three subshells namely: s-subshell , p-subshell and d-subshell.
For N- Shell, corresponding to Principal Q.N. n=4, l can be 0 ,1, 2 and 3. Here there are four subshells namely: s-subshell , p-subshell , d-subshell and f-subshell.
For O- Shell, corresponding to Principal Q.N. n=5, l can be 0 ,1, 2 , 3 and 4. Here there are five subshells namely: s-subshell , p-subshell , d-subshell , f-subshell and g-subshell.
For P- Shell, corresponding to Principal Q.N. n=6, l can be 0 ,1, 2 , 3 , 4 and 5. Here there are six subshells namely: s-subshell , p-subshell , d-subshell , f-subshell , g-subshell and h-subshell.
In nut-shell,the above information can be summarized by Table 2.5.
Table 2.5. Electron Distribution among the Sub-Shells.
| Sub-ShellOr Orbital |
l |
m l | Permissible statesw/o spin | Orbitalshape | Name |
|---|---|---|---|---|---|
| s | 0 | 0 | 1 | SPHERE | sharp |
| p | 1 | -1,0,+1 | 3 | TWODUMB BELLS | principal |
| d | 2 | -2,-1,0,+1,+2 | 5 | FOURDUMB BELLS | diffuse |
| f | 3 | -3,-2,-1, 0,+1,+2,+3 | 7 | EIGHTDUMB BELLS | fundamental |
The ORBITAL SHAPES of electron cloud for s-orbital, p-orbital, d-orbital and f-orbital are illustrated in Figure 2.3.
Spin Quantum Number: s = ±(1/2)ħ. This gives the quantization of the spin angular momentum. This Quantum Number ‘s’ has been illustrated in Figure 2.4.
For each unique set of (n, L, m) there can be two permissible electronic states:one corresponding to +(1/2)ħ and the second anti-parallel –(1/2)ħ.
Pauli Exclusion Principle clearly states that no two electrons can have the same four quantum numbers. Atleast one quantum number should differ.
For n = 1, l can only be 0 . This marks the First Period. This means spherically symmetrical electron cloud surrounding the nucleus. This means Orbital Angular Momentum will be always ZERO in first period.
Therefore in First Period, n=1, l = 0, m = 0, s = ± (1/2)ħ → this correspond to TWO elements H and He.
H is the first Group and He is the last Group in First Period. This is illustrated in Table 2.6.
Table 2.6. Elements of FIRST Period.
| FirstPeriod | 1 st Gr | 2 nd Gr | 3 rd Gr | 4 th Gr | 5 th Gr | 6 th Gr | 7 th Gr | 8 th Gr |
|---|---|---|---|---|---|---|---|---|
| Elements | H | - | - | - | - | - | - | He |
| s-orbitalbeing filled | 1s 1 | - | - | - | - | - | - | 2s 2 |
| K-ShellIs being Filled up | s-subshellin K-Shell | - | - | - | - | - | - | s-subshellin K-Shellis Full |
For n=2, l can be 0 and 1. This marks the Second Period.
Here we have K Shell which is already FULL and corresponds to He configuration and L-Shell is in the process of getting filled as shown in Table 2.7.
Table 2.7. Elements of SECOND Period.
| SecondPeriod | 1 st Gr | 2 nd Gr | 3 rd Gr | 4 th Gr | 5 th Gr | 6 th Gr | 7 th Gr | 8 th Gr |
|---|---|---|---|---|---|---|---|---|
| Elements | Li | Be | B | C | N | O | F | Ne |
| He corresponds to K-Shell | He2s 1 | He2s 2 | He2s 2 2p 1 | He2s 2 2p 2 | He2s 2 2p 3 | He2s 2 2p 4 | He2s 2 2p 5 | He2s 2 2p 6 |
| L-Shell Is being filled up. | s-subshellin L-Shell | s-subshellin L-Shellis Full | p-subshellin L-Shell | p-subshellin L-Shell | p-subshellin L-Shell | p-subshellin L-Shell | p-subshellin L-Shell | p-subshellin L-Shellis Full |
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