Ten Year of Atomic Structure

Chapter # 03                                                         Atomic Structure

1994

Q.3 (a) What are the weaknesses of Rutherford’s atomic theory?

(b) How have these defects been removed by Bohr’s atomic theory.

(c)  Determine an expression for the radius of hydrogen atom by applying Bohr’s atomic theory.

(d) Calculate the radius of second orbit of hydrogen atom in agnstrom unit.

1995

Q.3 (a) Derive an expression of radius of n^th orbit of hydrogen atom.

(b) Discuss the weakness of Rutherford atomic model.

(c)  Give the characteristic properties of alpha (a) rays.

(d) Calculate the radius of orbit of 3^rd for a hydrogen atom in angstrom unit.

Q.2 (c) Explain Pauli Exclusion principle.

1997

Q.2 (a) What information is obtained from the cathode rays experiment about the structure of atom? Describe the properties of cathode rays.

(b) Calculate the wave number of spectral line of hydrogen when an electron jumps from n = 4 to n = 2 (RH = 109678cm^-1)

(c)  State and explain Hund’s Rule.

(d) Select the correct answer for each.

                                        I).            Which quantum number describes the shape of an orbital?

                                     II).            Principle quantum number

                                  III).            Azmuthal quantum number.

1998

Q.2 (a) Write the short note on

(i)                Electro negativity

(ii)             Pauli Exclusion principle

       (b) Define Radio activity. Describe the Characteristic of Alpha OR Gamma rays.

Q.4 (a) Write down the postulates of Bohr’s Atomic theory and derive the expression of radius of hydrogen atom.

       (b) Define spectrum and discuss line spectrum.

       (c)        What rule and principles are violated in the following electronic configuration.

(i)                1S², 2S³

(ii)             1S², 2P²

(iii)           1S², 2S², 2P⁶, 3S², 3P⁶, 3d⁴

       (d) Draw the shape of the orbital for which 1 = 0

(e)  Make the correct sequence of orbital for the electronic configuration. According to (n+1) rule.

1999

Q.2 (a) What are cathode rays? How are their properties proved?

(b) How was the presence of proton detected and what are their     

      characteristic?

(c)  Write a short note on Radio activity or spectroscopy.

Q.4 (a) Define the following.

                   (ii) Pauli Exclusion Principle

                   (iii) Hund’s Rule

                   (iv) Quantum number

2000

Q.2 (a) What are assumptions of Bohr’s Atomic theory? How does this theory account for hydrogen spectrum?

       (b) Start from

                   K.E = ½ mv²                           P.E. = -Ze² /r

            Derive an expression for energy of an electron in n^th orbit of hydrogen

(c)  (i) Bohr’s radius is 0.529 A0. Find the radius of 3^rd orbit of Hydrogen atom.                                                 ₁₂

(ii) Complete                 ₄Be⁹ + ₂He⁴ ®     ₆C + ₆n¹

(iii) Which rule and principle is violated in

          1S², 2S², P_x ^­¯, 2P_y^­, 2P_z

(d) Write the short note:

· Pauli Exculsion principle

· X-rays and atomic number

2001

Q.3 (a) What are defects in Rutherford’s atomic model?

       (b) What happens when a current of high voltage is passes through gases at low pressure in the discharge tube? Prove that these rays.

(i)                Travel in straight line

(ii)             Are material in nature?

(iii)           Are electrons

9

      (c) Give the number of proton, neutron and electron for the following

3

26

                   ¹⁹F^{1-         56}Fe               ⁷Li¹⁺

      (d) Draw the shape of the s and p- orbital

      (e) Write the electronic configuration of the following:

                   (i) Cr (Z = 24)                            (ii) Cl^1- (Z = 17)

      (f) Write down the name of the spectral lines of a hydrogen atom.

2002

(Pre-Engineering)

Q.3 (a)        (i) How were neutron discovered? Give the reaction.

                   (ii) Compare the properties of Alpha, Beta and Gamma rays.

      (b) Write shot note on any two of the following.

(i)                Heisenberg’s Uncertainty principle

(ii)             Ionization potential

(iii)           Line spectrum

      (c) Describe Rutherford’s nuclear model of an atom with conclusions.

2002

 (Pre-Medical)

Q.2 (a) Derive an expression for the radius of Bhor’s orbit.

(b) What are cathode rays? How are they produced? Discuss their

     properties.

       (c) Give the number of proton, neutron and electron for the following.

                   ­_{24                       39}             

                     ₁₂Mg      and     ₁₉K

       (d) Write down the electronic configuration of:

                   Cr (Z = 24)    Li¹⁺ (Z = 3)          and           F^1- (Z = 9)

Q.8 (d) Write True of False.

(i)                Both the electrons in a helium atom have the same set of all the four quantum number.

(ii)             Alpha particle is helium nuclei.

2003

(Pre-Engineering)

Q.5 (a) Derive the expression for the energy of an electron in n^th orbit of Hydrogen atom; given that:

                              n² h²      ,       K.E. =  Ze²     ,         P.E = -Ze²
              4p ²m Ze²                       2r                             r

r

 

        (b)       Calculate the following:

(i)                The angular momentum of the electron in the first energy level of hydrogen atom (Plank’s constant h= 6.625 * 10^-27)

(ii)             The wave number of radiation emitted in Lyman series of hydrogen atom when electron jumps from 2^nd to 1^st orbit    (RH = 109678cm^1-)

(iii)           The radius of the third orbit of hydrogen atom using Bohr’s radius     (a_o = 0.529 A^o)

        (c) Write down the electronic configuration of:

                   ₂₉Cu           ₁₉K¹⁺        ₈O^2-

        (d) Define cathode rays. Give at least six properties of the cathode rays.

Q.8  (a) Differentiate the following:

                   · Lyman                 and                 · Balmer series

2003

(Pre-Medical)

Q.3 (a) Describe Rutherford’s atomic model and explain its basic assumptions and defects.

       (b) Describe the experiment, explaining the passage of electricity through Gases at low pressure.

       (c) Explain any two of the following:

(i)                Quantum Number

(ii)             X-rays and Atomic Number

(iii)           Electron Affinity

(e)                 Write down the electronic configuration for the ground state of the following:

Z = 19 ,           Z = 21 ,            Z = 6

2004

Q.2 (a) Give the number of proton, neutron and electron for the following.

                   _{23                 32                 19                 31}

                    ₁₁Na           ₁₆S                ₉F                ₁₅P

      (b) Derive and expression for the radius of Bhor’s orbit.

       (c) What principle and rule are followed in the electronic configuration of Atom?

(d) What are the shape of the orbital for which 1 = 0, and 1 = 1?

(e)  Differentiate between natural and artificial radioactivity.

Q.4 (d) Fill in the blanks.

                   i) The electronic configuration of N(1S², 2S², Px^­¯, 2Py^­, 2P_Z)

                      Show deviation form the ___________ rule.

                   ii) Isoelecetonic ions have different number of protons but the

same number of ____________.

2005

3-(a)  Write the postulates of Bohr’s Atomic Theory. Derive an expression for the energy of electron in                      an atom.

  (b)   Differentiate between the following:

          (i)      Principal Quantum Number and Azimuthal Quantum Number.

          (ii)     Continous Spectrum and Line Spectrum.

  (c)   (i)      Write the electronic configuration of:

                   (a) ₁₃Al⁺³     (b) ₂₉Cu                (c) ₁₇Cl^-1

          (ii)     Complete the equation:

                   ₄Be⁹ + ₂He⁴ _________ + ________

          (iii)    Which rule of Principle is violated in writing the following electronic configuration:

 

                   1s, 2s, 2px, 2py, 2pz

  (d)   State and explain the following:

          (i)      Pauli’s Exclusion Principle.

          (ii)     (n + 1) Rule.

          (iii)    Cathode Rays and their Properties.

2007

3-(a)  Write four properties of Cathode Rays along with their experimental proofs.

  (b)   (i)      How are positive rays generated in Cathod-Ray tube?

          (ii)     What is the relationship between X-Ray & Atomic No.?

  (c)   Distinguish between α & β rays.

  (d)   Fill in the blanks with the correct answers:

          (i)      The n + 1 value of 3d orbital is 5.

          (ii)      The electronic configration of. 7N 1s² 2s² 2px² 2py¹. The rule violated in this is                                    Hund’s Rule.

          (iii)    The ionization energy of ₄Be is greater than ₃Li.