Bsc CSIT Semester 1 – Physics – Unit 3: Fundamentals of Atomic Theory (8 Hrs.)

Give spectrum of Hydrogen atom and discuss its lines.

(a) How many atomic states are there in hydrogen with n=3?
(b) How are they distributed among the sub shells? Label each state with the appropriate set of quantum numbers n, l, ml, ms.
(c) Show that the number of states in a shell, that is, states having the same n, is given by 2n2. (Hint: 1+2+3+.......+n=n(n+1)/2).

What are

$\quad$ (a) the energy,

$\quad$(b) the momentum, and

$\quad$ (c) the tavelength of the photon that is
emitted when a hydrogen atom undergoes a transition from the state
$\quad$ n = 4 to n = 2?

An α particle is emitted from a radioactive nuclei with an energy of 6.8 MeV. Calculate its wavelength and compare it with the size of the emitting nucleus that has a radius of 8 x 10-15 m.

Describe the Frank-Hertz experiment. Discuss its result and outline limitations.

Describe Frank-Hertz experiment. Interpret how the results of this experiment advocate atomic model proposed by Bohr?

$\quad$ a.How many atomic states are there in hydrogen with n=3?

$\quad$ b.How are they distributed among the subshells? Label each state with the appropriates set of quantum

$\quad$ numbers n, 1,m,m

$\quad$ c.Show that the number of states in a shell, that is ,states having the same n. is given by $2n^2$.