line spectra Flashcards
what does the line spectra consist of?
discrete lines, each typical of the element concerned.
how can it be observed?
a tube contains a certain element, and when at appropriate voltages vaporises. The hot vapour emits light, the diffraction grating allows the spectrum to be viewed.
what does the line spectra show?
it provides evidence of the existence of quantized energy levels in the atom.
absorption spectrum
when white light is passed through a cooler vapour the light comes out as a continuous coloured spectrum with dark lines where the bright lines would have been in an emission spectrum.
How is an absorption spectrum formed?
when the vapour absorbs specific frequencies from white light.
Importance of the absorption spectrum
light from distant stars have been used to identify elements that are present in the star.
Doppler shift of line spectra from distant stars
red shift of line spectras shows that galaxies are moving away from each other, supporting the big bang theory.
