2.4 Atomic Emission Spectra Flashcards
How is an emission spectrum produced?
When hydrogen gas at low pressure is subjected to very high voltage in a discharge tube light is emitted by the gas producing an emission spectrum.
What is the emission spectrum for hydrogen like?
Spectrum consists of a series of sharp, bright lines on a dark background the lines get closer together at higher frequency/energy.
What does does the line spectrum produce for hydrogen mean?
That electrons in an atom are only allowed to have certain amounts of energy.
How does an emission spectrum arise?
Passage of the electric discharge causes an electron in an atom to be promoted to a higher energy level. Each line in the emission spectrum arises when an electron falls from a HIGHER to a LOWER energy level. As it returns to the lower energy level the extra energy is given out in the form of a PHOTON of light - this gives a line in the spectrum.
When do different series of lines arise?
When the electron fall down to different energy levels.
Why do the lines in the emission spectrum get closer together at higher energy?
Before the energy levels in the tom must get closer together in energy at higher energy.
What happens at the convergence limit?
The lines merge to form a continuum.
What happens beyond the convergence limit?
The electron can have any energy, the electron is no longer in the atom.
