Re: Are the atomic spectrums of the isotopes of an atom different from ...

Dear Leila
The atomic spectra of an atom are mostly independent of the particular
isotope.  This is because the main effect in determining the spectra
is the charge of the nucleus which is not influenced by the number of
neutrons, only the number of protons.  There are a few very small effects
which can lead to slight differences however.
1.) The mass of the nucleus is several thousand times bigger than that
of the electrons but it will still wobble a tiny amount as the electrons
orbit.  This slight motion of the nucleus will lower the energy of the
spectra by a few parts in a thousand, and hence, since different isotopes
have different masses, they will have slightly different spectral lines.
2.) The nucleus possess a magnetic moment which can interact with the
electrons which also have a magnetic moment.  The change to the spectra
caused by the magnetism of the nucleus is called hyperfine structure.
Since both protons and neutrons have magnetic moments, the hyperfine
structure is dependent on the isotope.
3.) The nucleus is a lot smaller than the orbit of the electrons,
but it is not a point.  Hence the shape of the charge distribution
in the nucleus will affect the energy of the electrons a little bit.
The exact distribution of electric charge in a nucleus is effected by
the number of neutrons
I hope this helps.   Larry