chemistry-class-11-unit-02-chapter-08-structure-of-the-atom-l-8-8-57jiayehoue

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Charge and mass of subatomic particles </primary>
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| Name     | Symbol | Absolute charge/C          |  Relative charge | Mass/kg                    | Mass/u   | Approx mass/u |
| -------- | -------| --------                   | --------         | --------                   | -------- |----------      |
|Electron  | $e$    |$-1.602176 \times 10^{-19}$ |$-1$              |$9.109382 \times 10^{-31}$  | $0.00054$|   $0$          |
| Proton   | $p$    |$+1.602176 \times 10^{-19}$ |$+1$              |$1.6726216 \times 10^{-27}$ | $1.00727$|   $1$          |
| Neutron  | $n$    | $0$                        |$0$               |$1.674927 \times 10^{-27}$  | $1.00867$|   $1$          |

- Calculate the mass and charge of one mole of electrons
- Find (a) the total number and (b) the total mass of protons in $34 \mathrm{mg}$ of $\mathrm{NH}_3$ at STP

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<footer style = "font-size: 18px"> $\rightarrow$ Structure of atom $\rightarrow$ <span style = "color:blue"> Charge and mass of subatomic particles </span> $\rightarrow$ Charge and mass of subatomic particles $\rightarrow$ Charge and mass of subatomic particles </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Charge and mass of subatomic particles </primary>
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- **Answer (b)** 
- ${NH}_3 \quad, {A}=179$
- $179 \text{ of  } {NH}_3 \quad 6.023 \times 10^{23} \quad {NH}_3  \text { molecules }$
- $34  {mg }  \text { of }{NH}_3 \quad \frac{6.023 \times 10^{23}}{17 \times 10^3} \times 34=12.046 \times 10^{20} { ~NH}_3 \text { molecules }$
- $ {NH}_3 \Rightarrow 10 \text { protons } \Rightarrow 34 {mg} {NH_3} \Rightarrow 1.2046 \times 10^{22} \text { protons }$
- $ \text { Mass of proton }=1.2046 \times 10^{22} \times 1.672 \times 10^{-27} {kg}$
- $\text { Mass of proton } =20.1{ mg} $

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<footer style = "font-size: 18px">Charge and mass of subatomic particles $\rightarrow$ Charge and mass of subatomic particles $\rightarrow$ <span style = "color:blue"> Charge and mass of subatomic particles </span> $\rightarrow$ Atomoic mass and atomic number $\rightarrow$ Atomoic mass and atomic number </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Wavelength - wavenumber-frequency-time period-energy </primary>
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- **Answer (c)**
- $\tau=2 \times 10^{-10} { s} \Rightarrow \nu=\frac{1}{\tau}=0.5 \times 10^{10} { s}^{-1}$
- $\nu=\frac{c}{\lambda} \Rightarrow \lambda=\frac{c}{\nu}=\frac{3 \times 10^8 { ms}^{-1}}{0.5 \times 10^{10} { s}^{-1}}=0.06 { m}$
- $\bar \nu=\frac{1}{\lambda}$

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<footer style = "font-size: 18px">Wavelength - wavenumber-frequency-time period-energy $\rightarrow$ Wavelength - wavenumber-frequency-time period-energy $\rightarrow$ <span style = "color:blue"> Wavelength - wavenumber-frequency-time period-energy </span> $\rightarrow$ Photoelectric effect $\rightarrow$ Photoelectric effect </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Photoelectric effect </primary>
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- **Question 4 -** A photon of wavelength $4 \times 10^{-7} \mathrm{~ m}$ strikes on metal surface , the work function of the metal being $2.13 \mathrm{eV}$. Calculate  
- (a) The energy of the photon (eV) ,  
- (b) The kinetic energy of the emission and   
- (c) The velocity of the photoelectron   $(\left.1 \mathrm{eV}=1.6020 \times 10^{-19} \mathrm{~ J}\right)$

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<footer style = "font-size: 18px">Wavelength - wavenumber-frequency-time period-energy $\rightarrow$ Wavelength - wavenumber-frequency-time period-energy $\rightarrow$ <span style = "color:blue"> Photoelectric effect </span> $\rightarrow$ Photoelectric effect $\rightarrow$ Photoelectric effect </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Photoelectric effect </primary>
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- **Answer (a)**
 - $ \lambda=4 \times 10^{-7} \mathrm{~ m} $
 - $ \phi_0=2.13 \mathrm{~ eV}$
 - $E=\frac{h c}{\lambda} =\frac{6.626 \times 10^{-34} \times 3 \times 10^8 {Js ~ ms}^{-1}}{4 \times 10^{-7} { m}}$
 - $E=4.07 \times 10^{-19} {J}=\frac{4.07 \times 10^{-19}}{1.602 \times 10^{-19}} {eV}=3.10 {eV}$

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<footer style = "font-size: 18px">Wavelength - wavenumber-frequency-time period-energy $\rightarrow$ Photoelectric effect $\rightarrow$ <span style = "color:blue"> Photoelectric effect </span> $\rightarrow$ Photoelectric effect $\rightarrow$ Photoelectric effect </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Hydrogen atom energy levels </primary>
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- **Answer (b)**
 - $ E_f=0 $
 - $E_i=E_4 \quad \Rightarrow \quad IE =\frac{2.18}{16} \times 10^{-18} { J}$
 - $IE=1.36 \times 10^{-19} { J}$

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<footer style = "font-size: 18px">Hydrogen atom energy levels $\rightarrow$ Hydrogen atom energy levels $\rightarrow$ <span style = "color:blue"> Hydrogen atom energy levels </span> $\rightarrow$ Hydrogen-like systems $\rightarrow$ De-brogile's hypothesis </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Hydrogen-like systems </primary>
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- **Question 6 -** Calculate the energy required for the following process ${He}^+ ({g}) \rightarrow {H}e^{2+}({g}) + {e}^-$
- **Answer**
 - $E_n=-2.18 \times 10^{-18}\left(\frac{Z^2}{n^2}\right) {J}$
 - ${E} = -2.18\times 10 ^{-18} \times 4 { J}$
 - $ E= \underbrace{-8.72 \times 10 ^{-18}} { J}$

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<footer style = "font-size: 18px">Hydrogen atom energy levels $\rightarrow$ Hydrogen atom energy levels $\rightarrow$ <span style = "color:blue"> Hydrogen-like systems </span> $\rightarrow$ De-brogile's hypothesis $\rightarrow$ Quantum numbers </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> De-brogile's hypothesis </primary>
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- **Question 7 -** The mass of an electron is $9.1\times 10^{-31}{ kg.}$ If its ${K.E}$ is $3.0 \times 10 ^{-25} { J}$ , calculate its wavelength $\lambda = \frac{h}{p} = \frac{h}{mv}$
- **Answer**
 - ${K E}= \frac{p^2}{2 m}=3 \times 10^{-25} { J}$
 - $ p^2=2 \times 9.11 \times 10^{-31} \times 3 \times 10^{-25} { J}  { kg}$
 - ${p}=7.39 \times 10^{-28} { kg} { m} { s}^{-1}$
 - $ \lambda=\frac{h}{p} =\frac{6.626 \times 10^{-34} {Js}}{7.39 \times 10^{-28} { kg} { m} {s}^{-1}}$
 - $\lambda=0.897 \times 10^{-6} { m} $
 - $\lambda=897 {nm}$

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<footer style = "font-size: 18px">Hydrogen atom energy levels $\rightarrow$ Hydrogen-like systems $\rightarrow$ <span style = "color:blue"> De-brogile's hypothesis </span> $\rightarrow$ Quantum numbers $\rightarrow$ Quantum numbers </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Electronic configuration </primary>
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- **Question 9 -** An atom of an element contains 29 electrons and 35 neutrons. Deduce 
- (a) The number of protons and 
- (b) The electronic configuration of the element
- **Answer**
 - $\underline{\text{ Increasing order of} ~n +l :}$
 - $1 s$ $2s$ $2 p$ $3 s$ $3 p$ $4 s$ $3 d$ $4 p$ $5 s \ldots$
 - $\text { Number of } p=29=z \quad {Cu}$
 - ${ }_{29}^{64} {Cu} \quad 1 s^2 \quad {2 s^2} \quad {2 p^6} \quad 3 s^2 \quad3 p^6 \quad 4 s \quad 3d$
 - $\underbrace{4s^2 \quad 3d^9} $
 - $4s^1 \quad 3d^{10}$

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<footer style = "font-size: 18px">Quantum numbers $\rightarrow$ Quantum numbers $\rightarrow$ <span style = "color:blue"> Electronic configuration </span> $\rightarrow$ Nodes in orbitals $\rightarrow$ Effective nuclear charge </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Nodes in orbitals </primary>
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- **Question 10 -** Arrange the following orbitals in increasing order of radial nodes , angular nodes, and total nodes - 1s, 2s, 2p, 3s, 3p, 3d
- $\text {Number of radial nodes} =n-1-1$
- $\text {Number of angular nodes}=1$
- $\text {Number  of nodes}=n-1$

- **Answer**

| Nodes                          | 1s | 2s | 2p | 3s | 3p |3d |
| --------                       | ---| ---| ---| ---| ---| --|
| $\text {Number of angular nodes}$ | 0  | 0  | 1  | 0  | 1  | 2 |
| $\text {Number of radial nodes}$  | 0  | 1  | 0  | 2  | 1  | 0 |
| $\text {Number of total nodes}$   | 0  | 1  | 1  | 2  | 2  | 2 |

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<footer style = "font-size: 18px">Quantum numbers $\rightarrow$ Electronic configuration $\rightarrow$ <span style = "color:blue"> Nodes in orbitals </span> $\rightarrow$ Effective nuclear charge $\rightarrow$ Thank you </footer>

### <Success style="font-size:25px"> Structure Of The Atom L-8 </Success>
### <primary style="font-size:24px"> Effective nuclear charge </primary>
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- **Question 11 -** Among the following pairs of orbitals which orbital will experience the larger effective nuclear charge ?
- (a) 1s and 2s$\quad$   
- (b) 4d and 4f $\quad$   
- (c) 3d and 3p  
- **Answer**
- (a) $ 1{s} > 2{s}$
- (b) $ 4{d} > 4{f}$
- (c) $ 3{p} > 3{d}$

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<footer style = "font-size: 18px">Electronic configuration $\rightarrow$ Nodes in orbitals $\rightarrow$ <span style = "color:blue"> Effective nuclear charge </span> $\rightarrow$ Thank you $\rightarrow$  </footer>