NIELS BOHR
Lived from: 1885 to 1962
Put forward atomic model in: 1913
Nickname for his model: Energy Level Model
Description of his model:
Bohr’s atom like Rutherford’s contained a dense, positive nucleus. He expanded on Rutherford’s ideas, turning his attention to describing the electron. He stated they moved in fixed, circular orbits (or energy levels) around the nucleus, these called electron shells. These shells were at set distances from the nucleus and were the same for all atoms. He stated they became larger the further away they are from the nucleus, and that electrons furthest from the nucleus have higher energy. He identified that an electron can jump from a lower orbit to a higher orbit by absorbing energy, this can be done in the forms of heat, light or electricity. These electrons then lose energy when they are allowed to cool, giving them the emission spectra for all different elements.
Lived from: 1885 to 1962
Put forward atomic model in: 1913
Nickname for his model: Energy Level Model
Description of his model:
Bohr’s atom like Rutherford’s contained a dense, positive nucleus. He expanded on Rutherford’s ideas, turning his attention to describing the electron. He stated they moved in fixed, circular orbits (or energy levels) around the nucleus, these called electron shells. These shells were at set distances from the nucleus and were the same for all atoms. He stated they became larger the further away they are from the nucleus, and that electrons furthest from the nucleus have higher energy. He identified that an electron can jump from a lower orbit to a higher orbit by absorbing energy, this can be done in the forms of heat, light or electricity. These electrons then lose energy when they are allowed to cool, giving them the emission spectra for all different elements.
Shells Added to the Atom
As you can see, the shells and levels that Niels Bohr discovered are visible in this model.
Try these Interactive Links About the Bohr Model:
1) www.cs.sbcc.edu/physics/solar/sciencesegment/bohratom.swf
2) http://spiff.rit.edu/classes/phys301/lectures/spec_lines/Atoms_Nav.swf
1) www.cs.sbcc.edu/physics/solar/sciencesegment/bohratom.swf
2) http://spiff.rit.edu/classes/phys301/lectures/spec_lines/Atoms_Nav.swf
More Information:
A simple definition of Bohr’s atomic model is: electrons orbit the nucleus at set distances. When an electron changes orbits, it does so in a sudden quantum leap. The energy difference between the initial and final orbit is emitted by the atom in bundles of electromagnetic radiation called photons. This model was proposed in 1913 by Niels Bohr and was really an expansion on the Rutherford model of 1911. The Rutherford model had several flaws that the Bohr model overcame.
The Bohr model was based on his observations of the atomic emissions spectrum of the hydrogen atom. When white light is diffracted with a prism, all the colors of the visible spectrum can be seen. Each color corresponds to a specific amount of energy; however when the light given off by the hydrogen atom was passed through a prism, only certain colors of light could be seen. This led Bohr to theorize that electrons only have certain energies in an atom and they had to be in energy levels. Bohr found the energy of the colors of light that the hydrogen atom released. He used these energies to find the energies that the single electron in the hydrogen atom could have. Bohr said that the electron had to release energy to change its energy so the differences between the energies of light seen in the atomic spectrum should correspond to the differences in energies of the energy levels.
Niels Bohr, a Danish scientist, explained this line spectrum while developing a model for the atom:
Bohr found that the closer an electron is to the nucleus, the less energy it needs, but the farther away it is, the more energy it needs. So Bohr numbered the electron’s energy levels. The higher the energy-level number, the farther away the electron is from the nucleus — and the higher the energy.
Bohr also found that the various energy levels can hold differing numbers of electrons: energy level 1 may hold up to 2 electrons, energy level 2 may hold up to 8 electrons, and so on.
The Bohr model works well for very simple atoms such as hydrogen (which has 1 electron) but not for more complex atoms.
A simple definition of Bohr’s atomic model is: electrons orbit the nucleus at set distances. When an electron changes orbits, it does so in a sudden quantum leap. The energy difference between the initial and final orbit is emitted by the atom in bundles of electromagnetic radiation called photons. This model was proposed in 1913 by Niels Bohr and was really an expansion on the Rutherford model of 1911. The Rutherford model had several flaws that the Bohr model overcame.
The Bohr model was based on his observations of the atomic emissions spectrum of the hydrogen atom. When white light is diffracted with a prism, all the colors of the visible spectrum can be seen. Each color corresponds to a specific amount of energy; however when the light given off by the hydrogen atom was passed through a prism, only certain colors of light could be seen. This led Bohr to theorize that electrons only have certain energies in an atom and they had to be in energy levels. Bohr found the energy of the colors of light that the hydrogen atom released. He used these energies to find the energies that the single electron in the hydrogen atom could have. Bohr said that the electron had to release energy to change its energy so the differences between the energies of light seen in the atomic spectrum should correspond to the differences in energies of the energy levels.
Niels Bohr, a Danish scientist, explained this line spectrum while developing a model for the atom:
- The Bohr model shows that the electrons in atoms are in orbits of differing energy around the nucleus (think of planets orbiting around the sun).
- Bohr used the term energy levels (or shells) to describe these orbits of differing energy. He said that the energy of an electron is quantized, meaning electrons can have one energy level or another but nothing in between.
- The energy level an electron normally occupies is called its ground state. But it can move to a higher-energy, less-stable level, or shell, by absorbing energy. This higher-energy, less-stable state is called the electron’s excited state.
- After it’s done being excited, the electron can return to its original ground state by releasing the energy it has absorbed, as shown in the diagram below.
- Sometimes the energy released by electrons occupies the portion of the electromagnetic spectrum (the range of wavelengths of energy) that humans detect as visible light. Slight variations in the amount of the energy are seen as light of different colors.
Bohr found that the closer an electron is to the nucleus, the less energy it needs, but the farther away it is, the more energy it needs. So Bohr numbered the electron’s energy levels. The higher the energy-level number, the farther away the electron is from the nucleus — and the higher the energy.
Bohr also found that the various energy levels can hold differing numbers of electrons: energy level 1 may hold up to 2 electrons, energy level 2 may hold up to 8 electrons, and so on.
The Bohr model works well for very simple atoms such as hydrogen (which has 1 electron) but not for more complex atoms.
Summary:
Niels Bohr was a Danish physicist he was from Copenhagen, Denmark. He proposed a model of the atom that is similar to the model of the solar system. The electrons go around the nucleus like planets orbit around the sun. All electrons have their energy levels – a certain distance from the nucleus.Each energy level can hold a certain number of electrons. Level 1 can hold 2 electrons, Level 2- 8 electrons, Level 3- 18 electrons, and level 4 – 32 electrons. The energy of electrons goes up from level 1 to other levels.When electrons release (lose) energy they go down a level. When electrons absorb (gain) energy, they go to a higher level. After a lot of hard work, Bohr was able to create a new version of the atomic structure which is still used even today to identify the basic characteristics of an atom.
Adapted from:
Bohr's Atomic Model
http://www.universetoday.com/46886/bohrs-atomic-model/
&
Atomic Structure: The Bohr Model
http://www.dummies.com/how-to/content/atomic-structure-the-bohr-model.html
Niels Bohr was a Danish physicist he was from Copenhagen, Denmark. He proposed a model of the atom that is similar to the model of the solar system. The electrons go around the nucleus like planets orbit around the sun. All electrons have their energy levels – a certain distance from the nucleus.Each energy level can hold a certain number of electrons. Level 1 can hold 2 electrons, Level 2- 8 electrons, Level 3- 18 electrons, and level 4 – 32 electrons. The energy of electrons goes up from level 1 to other levels.When electrons release (lose) energy they go down a level. When electrons absorb (gain) energy, they go to a higher level. After a lot of hard work, Bohr was able to create a new version of the atomic structure which is still used even today to identify the basic characteristics of an atom.
Adapted from:
Bohr's Atomic Model
http://www.universetoday.com/46886/bohrs-atomic-model/
&
Atomic Structure: The Bohr Model
http://www.dummies.com/how-to/content/atomic-structure-the-bohr-model.html
