ATOMS
Alpha-particle
scattering experiment; Rutherford's model of atom; Bohr model of hydrogen atom,
Expression for radius of nth possible orbit, velocity and energy of electron in
nth orbit, hydrogen line spectra (qualitative treatment only)
5MARKS
1. (i)With suitable diagram explain the alpha particle experiment and write the observation and conclusion from the graph.
(ii)plot the graph number of alpha particle pass through the gold foil vs scattering angle.
(iiI)Define impact parameter. Write its significance.
2. Derive the expression for Bohr’s velocity, radius and energy from Bohr’s 2ndpostulate.
3MARKS
1. The
total energy of an electron in the first excited state of the hydrogen atom is
about –3.4 eV.
I.
What is the kinetic energy of the electron in
this state?
II.
What is
the potential energy of the electron in this state?
III.
Which of the answers above would change if the
choice of the zero of potential energy is changed?
2. Using Rutherford’s model of the atom, derive the expression for the total energy of the electron in hydrogen atom. What is the significance of total negative energy possessed by the electron?
2MARKS
1. Write the drawbacks of Rrutheford model.
2. Find the ratio of longest wavelength Balmer series to the shortest wavelength of Paschen series.
3. If the energy of ground state of hydrogen atom is -13.6ev then find
I. Kinetic energy in 3rd excited state ?
II. Potential energy in 3rd orbit ?
4. Find the radii in the 2nd orbit of H-atom?
5. Write three postulate of Bohr’s model ?
6. Find the ratio of velocity in H-atom 3rdexcied state to 3rd orbit ?
7. What is least distance closest approach ? How its depend on mass?
.
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