|Class 11 Chemistry Structure of Atom||Emission And Absorbtion Spectra|
EMISSION AND ABSORBTION SPECTRA
Atomic spectra: Absorption and Emission spectra.
This is the phenomenon that gave serious blow to Rutherford model.It can be defined as: ‘splitting of light’ into various colours or colour bands is called spectra.”
When we see VIBGYOR the Violet colour merges into another and likewise other color merges into another.
So, in that case:
Atomic spectra are of two types
Emission spectra: It is obtained when emitted light is analyzed.The light is emitted when an atom is heated or electric current is passed.These are also referred as finger prints of atoms.
The apparatus is set as shown in figure:
When we analyze with spectrometer the spectra obtained is discontinuous. When white light is passed through the sample it absorbs few radiations and then transmitted light is analyzed.
Emission spectra of hydrogen
Rydberg gave the formula to determine the wavelength of these lines. That is:
Limiting line: the limiting line in H spectrum was when n2=infinity
Question 1: Calculate the wave length of the spectral line obtained in the spectrum of Li2+ ion when the transition takes place between two levels whose sum is 4 and the difference is 2?