# First Year Chemistry Atomic Structure Q 25. (a) What is de-Broglies wavelength of an electron in meters travelling at half a speed of light?\[\left[\mathrm{m}=9.109 \times 10^{-31} \mathrm{~kg} \mathrm{c}=3 \times 10^{8} \mathrm{~ms}^{-1}

Change the way you learn with Maqsad's classes. Local examples, engaging animations, and instant video solutions keep you on your toes and make learning fun like never before!

##### Q 25. (a) What is de-Broglies wavelength of an electron in meters travelling at half a speed of light?\[\left[\mathrm{m}=9.109 \times 10^{-31} \mathrm{~kg} \mathrm{c}=3 \times 10^{8} \mathrm{~ms}^{-1}\right]\]

Q11. (a) Hydrogen atom and \mathrm{He}^{+} are mono-electronic system but the size of \mathrm{He}^{+} is much smaller than \mathrm{H}^{+} why?

Q9. (a) Derive the following equations for hydrogen atom which are related to the(i) energy difference between two levels \mathrm{n}_{1} and \mathrm{n}_{2} .

(vii) In the ground state of an atom the electron is present(a) in the nucleus(b) in the second shell(c) nearest to the nucleus(d) farthest from the nucleus

Q 19 Bohrs equation for the radius of nth orbit of electron in hydrogen atom is\[\mathrm{r}_{\mathrm{n}}=\frac{\epsilon_{0} \mathrm{~h}^{2} \mathrm{n}^{2}}{\pi \mathrm{e}^{2} \mathrm{~m}}\](b) What is the distance travelled by the electron when it goes from n=2 to n=3 and n=9 ton =10 ?\[\left[\varepsilon_{0}=8.85 \times 10^{-12} \mathrm{c}^{2} \mathrm{~J}^{-1} \mathrm{~m}^{-1} \mathrm{~h}=6.624 \times .10^{-34} \mathrm{js} \pi=3.14 \mathrm{~m}=9.108 \times 10^{-31} \mathrm{~kg} \mathrm{e}=1.602 \times 10^{-19} \mathrm{c}\right]\] while doing calculations take care of units of energy parameter.\[\left[=\mathrm{kgm}^{2} \mathrm{~s}^{-2} \mathrm{c}=\mathrm{kg}^{1 / 2} \mathrm{~m}^{3 / 2} \mathrm{~s}^{-1}\right]\]

Q2. Fill in the blanks with suitable words.(i) \beta -particles are nothing but moving with a very high speed.(ii) The charge on one mole of electrons is coulombs.(iii) The mass of hydrogen atom is grams.(iv) The mass of one mole of electrons is(v) Energy is when electron jumps from higher to a lower orbit.(vi) The ionization energy of hydrogen atom can be calculated from model of atom.(vii) For d-subshell the azimuthal quantum number has value of(viii) The number of electrons in a given subshell is given by formula(ix) The electronic configuration of \mathrm{H}^{+} is

14. (a) The ionization potential of Lithium and potassium are 5.4 and 4.3 \mathrm{ev} . what do you predict for the I.P. of \mathrm{Na} .

Q9. (a) Derive the following equations for hydrogen atom which are related to the(iii) wave number of the photon when the electron jumps from n_{2} to n_{1} .

Q 4: Keeping in mind the discharge tube experiment answer the following questions.(b) Whichever gas is used in the discharge tube the nature of the cathode rays remains the same. Why?

4. What information about the electron in the atom is obtained from the fact that the emission spectra of the elements are frequently discontinuous?

Q8 Derive the formula for calculating the energy of an electron in nth orbit using Bohrs model. Keeping in view this formula explain the following:(b) Total energy of the bounded electron is also negative.

Q17 A photon of light with energy 10^{-19} \mathrm{~J} is emitted by a source of light.(a) Convert this energy into the wavelength frequency and wave number of the photon in terms of meters hertz and \mathrm{m}^{-1} respectively.

(x) When 6 d orbital is complete the entering electron goes into(a) 7 f (b) 7 \mathrm{~s} (c) 7 p (d) 7 d

4. Prove that modern theory of De Broglie is related with Einstein and Planks equations.

Q 23 Calculate the wave number of the photon when the electron jumps from(ii) \mathrm{n}=5 to \mathrm{n}=1 In which series of spectral lines and spectral regions these photons will appear.

(c) Write down the electronic configuration for the ground states of each of the following (i) N a(Z=11)

(e) Justify that the distance gaps between different orbits go on increasing from the lower to the higher orbits.

9. Explain the distinction between the following:(c) Ground state and excired state

12. What do you understand by the terms:(c) Electron affinity

(c) Write down the electronic configuration for the ground states of each of the following(iv) \mathrm{Mg}^{2+}(\mathrm{Z}=12) (v) \mathrm{Cl}^{-}(\mathrm{Z}=17) .

Q2. Fill in the blanks with suitable words.(i) \beta -particles are nothing but moving with a very high speed.(ii) The charge on one mole of electrons is coulombs.(iii) The mass of hydrogen atom is grams.(iv) The mass of one mole of electrons is(v) Energy is when electron jumps from higher to a lower orbit.(vi) The ionization energy of hydrogen atom can be calculated from model of atom.(vii) For d-subshell the azimuthal quantum number has value of(viii) The number of electrons in a given subshell is given by formula(ix) The electronic configuration of \mathrm{H}^{+} is

10. Describe the conuribution made by the following individuals toward the structure of atom (a) Rutherford

5. Electronic configuration is distribution of:(a) proton(b) neutron(c) electron(d) positron

Q5(a) Explain Millikans oil drop experiment to determine the charge of an electron.

Q 4: Keeping in mind the discharge tube experiment answer the following questions.(e) Why the positive rays are also called canal rays?

3. Criticize the following statement "An electron moves about the nucleus of an atom in a manner analogous to the movement of a planet about the sun"?

Q14. (a) Briefly discuss the wave mechanical model of atom. How has it given the idea of orbital. Compare orbit and orbital.

12. What do you understand by the terms:(b) Ionization potential

Q18 The formula for calculating the energy of an electron in hydrogen atom given by Bohrs model\[\mathrm{E}_{\mathrm{n}}=\frac{-\mathrm{m}^{2} \mathrm{e}^{4}}{8 \varepsilon_{0}^{2} \mathrm{~h}^{2} \mathrm{n}^{2}}\]Calculate the energy of the electron in first orbit of hydrogen atom. The values of various parameters are same as provided in Q19.