Bohr Theory

 The Bohr Theory was created by Niels Bohr. This theory established the first sound description of the behavior of electrons on atoms. Initially developed for the Hydrogen atom, the theory has been expanded and modified over the years. Based on the original Bohr Theory, Erwin Shrodinger has completed the most comprehensive description of the electronic structures of atoms. Schrodinger's ideas are covered in the Modern Theory of Atomic Structure. Following is a series of terms and concepts that relate to Bohr Theory.

 

 In order to make this set of web pages most useful, it is suggested that the reader start with a basic introduction to the Bohr Theory. The fundamental information about the theory is given as a specific presentation. After completing that brief presentation, the reader will then navigate back to this page where presentations on critical terminology is available.

Bohr Theory Presentation


 

Atomic Spectrum

 The Atomic Spectrum is a series of lines of color produced when light from an excited atom is passed through a prism. It is also known as a line spectrum.

Each element has its own unique atomic spectrum. Because of their unique nature, atomic spectra are also referred to as the "fingerprints of the elements." The series of lines of color that an atom will produce is related to the locations of the electrons on that atom and their relationship with the nucleus. Atomic spectra were fundamental pieces of experimental information used by chemists in the development of the electronic structures of atoms. By studying the colors emitted by the different elements, it is possible to work backwards to the sources of those colors. In this way it is possible to determine the electronic structures of the elements. Most of the basic information known today about electronic structures was derived from studying the light emitted by the atoms.

 The process of exciting an atom, involves adding energy to the atom. This can be done in a variety of ways. Simply heating a sample of an element up in an open flame will excite electrons. Passing electricity through a sample of an element will excite electrons. The colored lights observed when sky rockets explode are a result of burning gunpowder exciting electrons within atoms of elements packed with the gun powder.  

 

Continuous Spectrum

 A continuous spectrum will be a spectrum that contains all colors of light. It is commonly referred to as a "rainbow" when applied to the visible region of light. A single element does not produce a continuous spectrum. A continuous spectrum, or rainbow, when observed in nature, is usually the result of the spectra of many elements superimposed on top of each other. In addition, the spectrum produced by sun light in a continuous spectrum.


Discontinuous Spectrum

 A Discontinuous Spectrum will appear as a "rainbow" with certain colors missing. This type of spectrum is produced by each element individually. The locations of the colors that are present and the gaps in color serve as clues to the arrangements of electrons on the atoms. This is also referred to as a "line spectrum", or if coming from a single element, an "atomic spectrum."

Electromagnetic Radiation

 Electromagnetic Radiation, or emr, is basically another name for light. It is energy that is released by a charged object as it vibrates in a magnetic field. As electrons vibrate up and down on an atom, they will produce emr. Emr is described by three variables--energy, wavelength and frequency. By studying the emr produced by atoms it becomes possible to indirectly study the electronic structures of atoms.

 

Electromagnetic Radiation Spectrum

 The Electromagnetic Radiation Spectrum, or EMR Spectrum, is a full "rainbow" of all colors of light, both visible and non-visible. To a large degree it is a theoretical spectrum, in that no real system is capable of producing all colors of emr. The EMR Spectrum is generally broken down into three regions--visible, ultraviolet and infrared. By tradition, the spectrum is shown with the colors in order of increasing wavelengths, decreasing frequencies and decreasing energy values.


Energy Level
 An energy level is a specific location on an energy level diagram that corresponds to an allowed specific energy content of an electron. Bohr Theory said that the electron was restricted to existing only at specific levels of energy and would never be found with energy content between those levels. This component of the theory was based on work done by Max Planck.


Excited State

 The Excited State according to Bohr Theory is a position on an energy level diagram that contains more energy than the Ground State. When an electron is exposed to energy it may absorb some of that energy. If it does, it will rise up the energy level diagram to a new position that corresponds to the higher energy content. An electron in an excited state is not in its most stable position. An electron in an excited state will eventually return to the Ground State.

Electron Transition
   An electron transition is the movement of an electron from one energy level to another. If an electron moves from a low energy level to a higher energy level it does so by gaining energy. If it moves from a higher energy level to a lower energy level, it does so by releasing energy. The released energy is in the form of electromagnetic radiation. The energy content and wavelength of the released electromagnetic radiation will correspond to the difference in energy content of the two levels. This transition is also known as a Quantum Jump.

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Updated June 30, 2008