Bohr atomic model and limitations?
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electron revolves around the nucleus on a fixed circular path called Orbit
electron revolves in thoes circular path in which their angular momentum is whole number multiple of h/2π
energy is emitted or observed only when electron goes from one energy level to another energy level .
limitations....
it could not explain the stark effect and zeeman effect .
it could not explain the ability of atom to form covalent bond .
it could not explain the spectrum of atom other than the hydrogen .
electron revolves in thoes circular path in which their angular momentum is whole number multiple of h/2π
energy is emitted or observed only when electron goes from one energy level to another energy level .
limitations....
it could not explain the stark effect and zeeman effect .
it could not explain the ability of atom to form covalent bond .
it could not explain the spectrum of atom other than the hydrogen .
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Niels Bohr introduced the atomic Hydrogen model in 1913. He described it as a positively charged nucleus, comprised of protons and neutrons, surrounded by a negatively charged electron cloud. In the model, electrons orbit the nucleus in atomic shells. The atom is held together by electrostatic forces between the positive nucleus and negative surroundings.
Hydrogen Energy Levels
The Bohr model is used to describe the structure of hydrogen energy levels. The image below represents shell structure, where each shell is associated with principal quantum number n. The energy levels presented correspond with each shell. The amount of energy in each level is reported in eV, and the maxiumum energy is the ionization energy of 13.598eV.
Salient features of Bohr’s atomic model are:
Electrons revolve around the nucleus in stable orbits without emission of radiant energy. Each orbit has a definite energy and is called an energy shell or energy level.
An orbit or energy level is designated as K, L, M, N shells. When the electron is in the lowest energy level, it is said to be in the ground state.
An electron emits or absorbs energy when it jumps from one orbit or energy level to another. When it jumps from a higher energy level to lower energy level it emits energy while it absorbs energy when it jumps from a lower energy level to a higher energy level.
The energy absorbed or emitted is equal to the difference between the energies of the two energy levels (E1, E2) and is determined by Plank’s equation.
Limitations of the Bohr Model
Limitations of Bohr Atomic Model Theory
It violates the Heisenberg Uncertainty Principle. The Bohr atomic model theory considers electrons to have both a known radius and orbit i.e. known position and momentum at the same time, which is impossible according to Heisenberg.
The Bohr atomic model theory made correct predictions for smaller sized atoms like hydrogen, but poor spectral predictions are obtained when larger atoms are considered.
It failed to explain the Zeeman effect when the spectral line is split into several components in the presence of a magnetic field.
It failed to explain the Stark effect when the spectral line gets split up into fine lines in the presence of an electric field
Hydrogen Energy Levels
The Bohr model is used to describe the structure of hydrogen energy levels. The image below represents shell structure, where each shell is associated with principal quantum number n. The energy levels presented correspond with each shell. The amount of energy in each level is reported in eV, and the maxiumum energy is the ionization energy of 13.598eV.
Salient features of Bohr’s atomic model are:
Electrons revolve around the nucleus in stable orbits without emission of radiant energy. Each orbit has a definite energy and is called an energy shell or energy level.
An orbit or energy level is designated as K, L, M, N shells. When the electron is in the lowest energy level, it is said to be in the ground state.
An electron emits or absorbs energy when it jumps from one orbit or energy level to another. When it jumps from a higher energy level to lower energy level it emits energy while it absorbs energy when it jumps from a lower energy level to a higher energy level.
The energy absorbed or emitted is equal to the difference between the energies of the two energy levels (E1, E2) and is determined by Plank’s equation.
Limitations of the Bohr Model
Limitations of Bohr Atomic Model Theory
It violates the Heisenberg Uncertainty Principle. The Bohr atomic model theory considers electrons to have both a known radius and orbit i.e. known position and momentum at the same time, which is impossible according to Heisenberg.
The Bohr atomic model theory made correct predictions for smaller sized atoms like hydrogen, but poor spectral predictions are obtained when larger atoms are considered.
It failed to explain the Zeeman effect when the spectral line is split into several components in the presence of a magnetic field.
It failed to explain the Stark effect when the spectral line gets split up into fine lines in the presence of an electric field
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