chemistry-class-11-unit-02-chapter-07-structure-of-the-atom-l-7-8-gh9gwvjz2ni

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Screening effect </primary>
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- Increasing order of energy of orbitals 
- $ 1s\hspace{1mm}2s \hspace{1mm} 2p \hspace{1mm} 3s \hspace{1mm} 3p \hspace{1mm} 4s \hspace{1mm} 3d\hspace{1mm} 4p \hspace{1mm} 5s \hspace{1mm} 4d \hspace{1mm} 5p \hspace{1mm}6s \hspace{1mm} 4f \hspace{1mm} 5d \hspace{1mm} 6p $
- Nucleus has 
 - Z $-$ number of protons
 - $Z_e$ $-$ charge of nucleus

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<footer style = "font-size: 18px"> $\rightarrow$ Structure of atom $\rightarrow$ <span style = "color:blue"> Screening effect </span> $\rightarrow$ Screening effect $\rightarrow$ Screening effect </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Trend in order of energy in orbital </primary>
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- $ 1s\hspace{1mm}2s \hspace{1mm} 2p \hspace{1mm} 3s \hspace{1mm} 3p \hspace{1mm} 4s \hspace{1mm} 3d\hspace{1mm} 4p \hspace{1mm} 5s \hspace{1mm} 4d \hspace{1mm} 5p \hspace{1mm}6s \hspace{1mm} 4f \hspace{1mm} 5d \hspace{1mm} 6p $
- For lower orbital quantum number , when s is zero electron can penetrate much effectively closer to the nucleus
- $\sigma $ - 3S < 3P < 3d
- $Z_{eff} - $ 3S > 3P > 3d

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<footer style = "font-size: 18px">Screening effect $\rightarrow$ Screening effect $\rightarrow$ <span style = "color:blue"> Trend in order of energy in orbital </span> $\rightarrow$ Filling of electrons in orbitals $\rightarrow$ Filling of electrons in orbitals </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Filling of electrons in orbitals </primary>
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- Building up principle (aufbau principle)
 - The orbitals are filled in the order of their increasing energy
 - $ 1s\hspace{1mm}2s \hspace{1mm} 2p \hspace{1mm} 3s \hspace{1mm} 3p \hspace{1mm} 4s \hspace{1mm} 3d\hspace{1mm} 4p \hspace{1mm} 5s \hspace{1mm} 4d \hspace{1mm} 5p \hspace{1mm}6s \hspace{1mm} 4f \hspace{1mm} 5d \hspace{1mm} 6p $ </p>

- H -$1s^1$
   - He -$1s^2$
   - Li -$ 1s^2 2s^1$
   - Na -$1s^2 2s^2 2p^6 3s^1$

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<footer style = "font-size: 18px">Filling of electrons in orbitals $\rightarrow$ Filling of electrons in orbitals $\rightarrow$ <span style = "color:blue"> Filling of electrons in orbitals </span> $\rightarrow$ Periodic table $\rightarrow$ Hund's rule of maximum spin multiplicity </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Hund's rule of maximum spin multiplicity </primary>
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- When  more than one orbital has the same  energy , electrons are filled in the separate orbital and carry parallel spins
- $6^C - 1s^2 2s^2 2p^2$

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<footer style = "font-size: 18px">Filling of electrons in orbitals $\rightarrow$ Periodic table $\rightarrow$ <span style = "color:blue"> Hund's rule of maximum spin multiplicity </span> $\rightarrow$ Hund's rule of maximum spin multiplicity $\rightarrow$ Hund's rule of maximum spin multiplicity </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Hund's rule of maximum spin multiplicity </primary>
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- $7^N - 1S^2 2s^2 2p^3$

- $p^3 , d^5 $&$ f^7 $ shells - half-filled shells

- half-filled shells & full-filled shells are most stable

- $24^{Cr} - 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^4$

-  $\underbrace{[Ar]}_{core}$ $\underbrace {4s^2 3d^4} _{valence}$ ( less stable )

- $[Ar] 4s^1 3d^5$ ( more stable )

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<footer style = "font-size: 18px">Periodic table $\rightarrow$ Hund's rule of maximum spin multiplicity $\rightarrow$ <span style = "color:blue"> Hund's rule of maximum spin multiplicity </span> $\rightarrow$ Hund's rule of maximum spin multiplicity $\rightarrow$ Topics covered </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Hund's rule of maximum spin multiplicity </primary>
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- $29^{Cu} - [Ar] 4s^2 3d^9 \rightarrow [Ar]4s^1 3d^{10}$

- $64^{Gd} - [54^{Xe}] 10 e^-$

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<footer style = "font-size: 18px">Hund's rule of maximum spin multiplicity $\rightarrow$ Hund's rule of maximum spin multiplicity $\rightarrow$ <span style = "color:blue"> Hund's rule of maximum spin multiplicity </span> $\rightarrow$ Topics covered $\rightarrow$ Problems </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Topics covered </primary>
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- Discovery of sub-atomic particles
- Different models of atom - (Dalton's model , Plum-pudding model , Rutherford model , Bohr model)
- Light is both a wave and a particle
- De Broglie hypothesis
- Heisenberg's uncertainty principle
- Quantum mechanical model of atom
- Solution of schrodinger equation-orbitals and their energy
- Quantum numbers
- Energy ordering of orbitals and electron correlation
- Electronic structure

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<footer style = "font-size: 18px">Hund's rule of maximum spin multiplicity $\rightarrow$ Hund's rule of maximum spin multiplicity $\rightarrow$ <span style = "color:blue"> Topics covered </span> $\rightarrow$ Problems $\rightarrow$ Problems </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Problems </primary>
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- **Problem 1** - The hydrogen-like species $Li^{2+}$ is in a spherically symmetric state $S_1$ with one radial node. Upon abosrbing light the ion undergoes transition to a state $S_2$. The state $S_2$ has one radial node and its energy is equal to the ground state energy of the hydrogen atom

- **i)** The state $S_1$ is
- A) 1s
- B) 2s
- C) 2p
- D) 3s
- **Ans** B) 2s

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<footer style = "font-size: 18px">Hund's rule of maximum spin multiplicity $\rightarrow$ Topics covered $\rightarrow$ <span style = "color:blue"> Problems </span> $\rightarrow$ Problems $\rightarrow$ Problems </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
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- **Problem 5** - The work function $(\phi)$ of some metals is listed below. The number of metals which will show photoelectric effect when light of 300 nm wavelength falls on the metal is

| Metal  | Li       | Na       |K       | Mg    |    Cu |Ag | Fe      | Pt      | W        |
| -------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- |
| $\phi (ev)$   | 2.4     | 2.3     | 2.2    | 3.7     | 4.8    | 4.3   | 4.7   | 6.3     | 4.75   |

- **Ans** -  $ \lambda = 300 nm$
- E = ? = $\frac {hC}{\lambda}$ = 4.13 ev
- The number of metals which will show photoelectric effect is 4

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<footer style = "font-size: 18px">Problems $\rightarrow$ Problems $\rightarrow$ <span style = "color:blue"> Problems </span> $\rightarrow$ Problems $\rightarrow$ Thank you </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-7 </Success>
### <primary style="font-size:24px"> Problems </primary>
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- **Problem 6** - The atomic masses of He and Ne are 4 and 20 amu respectively. The value of the de broglie wavelength of He gas  at $-73^\circ C$ is "M" times that of the de broglie wavelength of Ne at $727^\circ C$. M is

- **Ans -** 
 - $T_{Ne}= 727^\circ C $= 1000Kv 
 - $ T_{He} = -73^\circ C = 200Kv$
 - $\lambda = \frac {h}{mv}=\frac {h}{p}$
 - $\frac {\lambda_{He}}{\lambda_{Ne}} =?=\frac {P_{Ne}}{P_{He}}$
 - $E_k = \frac {3}{2}KT$
 - $E_k = \frac {p^2}{2m}\rightarrow p=\sqrt {2mE_k}$
 - $\frac {P_Ne}{P_He}=\sqrt{\frac{2.m_{Ne}.\frac{3}{2}k.1000}{2.m_{He}.\frac{3}{2}k.200}}$
 - =$\sqrt{\frac {20}{4}.5}$ $\quad$   $=5$

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<footer style = "font-size: 18px">Problems $\rightarrow$ Problems $\rightarrow$ <span style = "color:blue"> Problems </span> $\rightarrow$ Thank you $\rightarrow$  </footer>