Niels Bohr

Niels Bohr is a scientist that revolutionized the way we look at atoms today. He won the 1922 Nobel prize in physics.

1,759 Questions
Chemistry
Atoms and Atomic Structure
Niels Bohr

What is the Bohr model of the atom?

The Bohr model of the atom is based on four fundamental postulates. Although he did not claim to explain or prove these postulates, Bohr found that by applying them, he could predict the properties of single-electron atoms and ions to an amazing degree of accuracy. Using the Bohr model, it is possible to accurately predict the energy levels of all one-electron atoms and ions, such as H, He+, Li2+ Be3+, B4+, C5+, etc.

The four key postulates of Bohr's theory are:

1) Atoms have well-defined electron orbits.

2) Atoms do not radiate.

3) Electrons travel in circular orbits with specific angular momenta, and only certain values are possible (angular momentum is quantized).

4) As electrons go from one orbit to the next, energy is either absorbed or released by the atom.

The quantized angular momentum can be written as:

I = n * (h/2*pi)

where I is the angular momentum, n is any integer, h is Planck's constant, and pi is the number pi, or 3.14159.

See Web Links and Related QuestionsSee the Related Questions and Web Links to the left for the answer. Overview of the Bohr ModelNiels Bohr proposed the Bohr Model of the Atom in 1915. Because the Bohr Model is a modification of the earlier Rutherford Model, some people call Bohr's Model the Rutherford-Bohr Model. The modern model of the atom is based on quantum mechanics. The Bohr Model contains some errors, but it is important because it describes most of the accepted features of atomic theory without all of the high-level math of the modern version. Unlike earlier models, the Bohr Model explains the Rydberg formula for the spectral emission lines of atomic hydrogen.

The Bohr Model is a planetary model in which the negatively-charged electrons orbit a small, positively-charged nucleus similar to the planets orbiting the Sun (except that the orbits are not planar). The gravitational force of the solar system is mathematically akin to the Coulomb (electrical) force between the positively-charged nucleus and the negatively-charged electrons.

Main Points of the Bohr Model
  • Electrons orbit the nucleus in orbits that have a set size and energy.
  • The energy of the orbit is related to its size. The lowest energy is found in the smallest orbit.
  • Radiation is absorbed or emitted when an electron moves from one orbit to another. Bohr Model of HydrogenThe simplest example of the Bohr Model is for the hydrogen atom (Z = 1) or for a hydrogen-like ion (Z > 1), in which a negatively-charged electron orbits a small positively-charged nucleus. Electromagnetic energy will be absorbed or emitted if an electron moves from one orbit to another. Only certain electron orbits are permitted. The radius of the possible orbits increases as n2, where n is the principal quantum number. The 3 → 2 transition produces the first line of the Balmer series. For hydrogen (Z = 1) this produces a photon having wavelength 656 nm (red light).
Problems with the Bohr Model
    • It violates the Heisenberg Uncertainty Principle because it considers electrons to have both a known radius and orbit.
    • The Bohr Model provides an incorrect value for the ground state orbital angular momentum.
    • It makes poor predictions regarding the spectra of larger atoms.
    • It does not predict the relative intensities of spectral lines.
    • The Bohr Model does not explain fine structure and hyperfine structure in spectral lines.
    • It does not explain the Zeeman Effect.
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Niels Bohr

When did Niels Bohr discover the electron cloud?

In 1912 a Danish physicist, Niels Bohr came up with a theory that said the electrons do not spiral into the nucleus and came up with some rules for what does happen. (This began a new approach to science because for the first time rules had to fit the observation regardless of how they conflicted with the theories of the time.

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Chemistry
Scientists
Niels Bohr

What year did Niels Bohr invent Theory of the Atom?

State the relation between atomic number, mass number and number of neutrons in an atom.

Edit: Somethings got mixed up here. The answer to the "Bohr" question is "1913". That's when he came up with a model for the Hydrogen atom, at least.

Actually, I've seen various dates for this from 1912 and 1915, but I think

that 1913 is probably correct.

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Chemistry
Periodic Table
Niels Bohr

How does the Bohr model of the atom relate to the Periodic Table?

The Bohr model of the atom places electrons in orbits or "shells." Elements in the first period only have electrons in the first shell. Elements in the second period have electrons in the first two shells. Elements in the third period have electrons in the first three shells, and so on.

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Niels Bohr
Celebrity Births Deaths and Ages

Who was Niels Bohr and what did he do?

Nils Bohr designed an atomic model but eventually someone came up with an even more accurate model. He achieved the Nobel prize for physics.

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Chemistry
Scientists
Niels Bohr

Calculte the radius of bohrs second orbit for He plus cation?

1.058

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Niels Bohr

What schools did Niels Bohr attend at?

Copenhagen university

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Niels Bohr

What year did niels bohr make his discovery?

He formulated his atomic model (electrons orbiting the nucleus) in 1913.

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Science Experiments
Atoms and Atomic Structure
Niels Bohr

What experiments did Niels Bohr do that lead him to create his model of the atom?

See http://www.answers.com/topic/niels-bohr for information that should help.

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Math and Arithmetic
Chemistry
Niels Bohr

Drawbacks of neil bohr's atomic model?

1. It could not explain the atomic spectram energy of the elements other than 'HYDROGEN'.

2. It could not explain the brightness of the atomic spectral lines.

3. It could not explain the formation of chemical bonds.

4.

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Niels Bohr

How did Niels Bohr use spectra to determine energy levels of atoms and ions?

When a gas is excited in an electrical discharge, light is emitted (this is essentially how neon lamps work). Niels Bohr looked at this emitted light using a spectrograph, which separates different wavelengths of light (just a like a simple triangular prism). Atoms, such as hydrogen or neon, emit very specific patterns of light. When you separate the wavelengths, you see a pattern of very sharp lines of light at only certain wavelengths and not others. In other words, the atoms emit only certain wavelengths of light, resulting in a series of lines when you look at the light through a spectrograph. Bohr looked at these lines and managed to figure out the pattern that determined which wavelengths were observed. He said that the light emitted was due to transitions between energy levels in the atoms, and the wavelength of light corresponded to the energy difference between the two states involved in the transition. In this way, he figured out the equation to predict the spacing between all of the energy levels of any one-electron atom or ion. His model was quite successful, and he was able to predict which lines you would see for things that hadn't even been measured yet (a good test for any theory!). Surprisingly, although he figured out the pattern so well, he didn't actually know what the patterns were really due to. In fact, he had to make assumptions that turned out to be completely false! However, despite these errors (which were corrected when quantum mechanics was developed), the Bohr model of the atom is very useful for many applications. His model does NOT work well for multi-electron atoms/ions, which unfortunately includes the large majority of atoms and ions! You need quantum mechanics for that!

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Inventions
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Niels Bohr

How did bohr make his discovery?

he did not do an experiment, he made an equation

757677
Cadillac
Niels Bohr

What model is a Cadillac 68 special?

It's the Calais Edition

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Albert Einstein
Alfred Nobel
Niels Bohr

Local foreign biologist 5?

Charles Darwin-(1809-1882) England- Evolutionist famous for his theory 'survival of the fittest' Gregor Mendel-(1822-1884)Czech Republic- Genetics, botanist who discovered 'inherited traits' by cross-breeding pea plants Louis Pasteur- (1822-1895) France- Microbiologist who created 'pasteurization' (a process that kills microbes via heat) Roger W Sperry (1913-1994), America- neuropsychologist, winner of the 1981 Nobel Prize in Physiology or Medicine for his research on the split-brain Robert Hooke-(1635-1703) England - Cytologist who researched cells and actually coined the term 'cell." He also invented the reflecting microscope Anton van Leeuwenhoek-(1632-1723) Holland Cytologist who invented various single lens microscopes and discovered various microbes (protists) Carolus Linnaeus- (1707-1778) SwedenFather of Taxonomy Jane Goodall (1934- present) England- ethologist who studied Chimp behavior- lead authority in primatology John James Audobon (1785-1851) Santo Domingo- ornithologist and inspiration of the Audobon Society- An organization whose goal is the research and protection of bird species

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neuroplasticity

Henry Suter- (1841-1918) New Zealand zoologist, naturalist and palaeontologist and malacologist

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Chemistry
Atoms and Atomic Structure
Niels Bohr

What is another name for Bohr's model?

the planetery model

676869
Business Accounting and Bookkeeping
Mathematical Finance
Niels Bohr

What are the shortcomings of the binomial pricing model?

b) Binomial pricing model doesnt provide for the possibility of price of the underlying remaining the same between two consecutive time points (it assumes that either the price could go up or could come down; it completely ignores the possibility of the price not changing at all) a) Binomial pricing model breaks up the time to the expiry of option in to a limited number of time intervals and hence, the price calculated through binomial trees is more of a broad approximation of the actual price. (Compare this with Black Scholes (BS) Model which gives a more accurate approximation because the BS model involves breaking the time to expiry into infinitesimaly small time intervals).

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Niels Bohr

What did bohr's theory help explain?

physics!

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Relationships
History of Science
Niels Bohr

When did Niels Bohr the Danish scientist die?

November 18, 1962

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Eyes
History of Science
Charles Darwin
Niels Bohr

Explain Electronic theory of colors?

Electronic Color Theory"Electronic color theory" is a recent misnomer for additive color theory. Additive color theory predicts what colors will be perceived when different colors of light are mixed. It is differentiated from subtractive color theory, which predicts what colors will be perceived when different colors of pigment are mixed.

Additive color theory has been around for about 150 years, since it was first proposed and demonstrated by James Clerk Maxwell. It has recently been called "electronic color theory" in some undergraduate computer science courses, since it is most commonly applied to the light emitted by a CRT, LCD or plasma television and computer displays.

It has no relevance to Rutherford's model of the atom.
Nucleus surrounded by moving electronsErnest Rutherford performed a famous experiment which demonstrated that atoms had a small positively charged central nucleus surrounded by negatively charged electrons. Based on this experiment, he proposed a model of the atom in which electrons moved in the space around the central nucleus.

Rutherford's experiments didn't really contribute to the theory of electron orbitals really. He really established that the atom is mostly empty space, but what is solid, is very solid (in other the words, the nucleus is very small but most of the mass of the atom is in the nucleus). However, he discovered nothing where electrons are found atoms or the shapes of orbitals, or that orbitals even existed. That was really the work of Niels Bohr and those that followed him.


See the Related Questions for more information about Rutherford, his experiments and atomic structure.
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Cars & Vehicles
Mercedes-Benz SLK-Class
Niels Bohr

What models are out there?

Old body style slk 230 kompressor. (I-4) slk 320 (v-6) slk 32 amg (v-6) New body style slk 280 (new v-6) slk 350 (new v-6) slk 55amg (v-8)

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Physics
Niels Bohr

How can you make a Bohr model?

Answer

Like for school?

You can take a medium sized styrofoam ball and cut some pipe cleaners up and stick them in the ball, about four should be good. Then take a full sized pipe cleaner and wrap it into a circle then use a hot glue gun to conect the ends. Then glue the little pipe cleaners to the circle pipe cleaner. Next take little beads ( the proper amount of electrons ) and glue them to the circle pipe cleaner. But always remember that you can only put two electrons on the first ring. Then on the secound ring ( if needed ) put up to eight electrons, then from there on all of the rings can only hold eight electrons.

I really hope this helped :)

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Chemistry
Niels Bohr

An electrons path around the nucleus defines its?

An electron's path around the nucleus defines it's energy level.

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Niels Bohr

What contribution did Niels Bohr make to atomic theory?

He made a model of the atom, with electrons circling the nucleus.

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Chemistry
Atoms and Atomic Structure
Niels Bohr

How does the Bohr model of the atom explain light given off in line spectra?

The difference in energy between the energy levels determines color of light emitted when an electron moves from one energy level to another.

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Niels Bohr

Does the Bohr model work for all elements?

yes,

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