Chemistry - Niels Bohr and emission/absorption of energy
Niels Bohr and emission/absorption of energy
Niels Bohr refined the description of electron behaviour as it applied to
Rutherford's model of the atom.
He searched for an explanation of the emission spectrum of hydrogen. The
spectrum contains a series of lines, each representing certain distinct
quantities of energy.
Bohr used the emission spectrum of hydrogen atoms as the basis of his
theory that electrons in atoms could only move in
Each of these orbits in a hydrogen atom was called a stationary state.
Each line on the emission spectrum of hydrogen essentially represented the
transition of an electron from one or another of these stationary states
Electrons could be in one available stationary state (energy level) or
another but not in between. Atoms either as electrons moved to energy
levels further from the nucleus or as electrons moved to energy levels
closer to the nucleus.
Emission spectra are produced when atoms are returning from an to their
ground state, which has all electrons as close to the nucleus as possible.
When an electron moves from an energy level far from the nucleus to an
energy level closer to the nucleus, a (quantum of energy) equal to the
difference between the energy levels is
In atoms, some electrons are further from the nucleus than they would
like to be. Where atoms are excited by the addition of energy, electrons
can jump from energy levels close to the nucleus to energy levels further
away. This jump involves the absorption of a photon of energy equal to the
difference between the levels. Such behavior shows up on an absorption
The concepts of quanta of energy, absorption spectra and emission spectra
are all closely associated with the location of electrons around the
nucleus of an atom.
A quantum of energy is absorbed when an electron moves from a location
close to the nucleus to one further from the nucleus, or emitted when an
electron moves from a location far from the nucleus to one closer to the
Each line on an absorption or emission spectrum corresponds to the
movement of an electron between defined electron locations or energy
levels. Each black line on an absorption spectrum occurs at a wavelength of
visible (white) light absorbed by the element involved. When this element
emits light after being excited, the will show coloured lines (on a black
background) at exactly the same wavelengths at which the black lines occur
on the element's absorption spectrum.
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