explain bohrs atomic model with postulates
Answers
In order to explain the stability of an atom, Neils Bohr gave a new arrangement of electrons in the atom in 1913. According to Neils Bohr, the electrons could revolve around the nucleus in only 'certain orbits' (energy levels), each orbit having a different radius.
When an electron is revolving in a particular orbit or particular energy level around the nucleus, the electron does not radiate energy (lose energy) even though it has accelerated motion around the nucleus.
postulates are:-
The important postulates in his theory are,
Electrons revolve round the nucleus with definite velocities in concentric circular orbits situated at definite distances from the nucleus. The energy of an electron in a certain orbit remains constant. As long as it remains in that orbit, it neither emits nor absorbs energy. These are termed stationary states or main energy states.
Bohr proposed that the angular momentum of an electron is quantized. Thus, the motion of an electron is restricted to those orbits where its angular momentum is an integral multiple of h2πh2π, where h is Planck’s constant.
Thus we have the relationship mvr = nh2πnh2π, where m is mass of electron, v is velocity of electron of said orbit, r is radius of that orbit, n is a simple integer.
The stationary states or allowed energy levels are only those where n = 1, 2, 3, …… This is called Bohr quantum condition.
The energy of an electron changes only when it moves from one orbit to another. An electronic transition from an inner orbit to outer orbit involves absorption of energy. Similarly, when an electron jumps from an outer orbit to inner orbit it releases energy, which is equal to the difference between the two energy levels.
The energy thus released in the form of a radiation of a certain frequency appears in the form a line in the atomic spectrum. If the energy of an electron in the outer orbit (n2) is E2 and energy of electron in the inner orbit (n1) is E1 then E2 - E1 = ΔE = hνν.
The value of n could be small integers 1, 2, 3 and these correspond to the first, second, third, and so on. Quantum states are shells for the electron; n is termed as principal quantum number.
Based on the Bohr theory Bohr calculated the radii of the various orbits and the energies associated with the electrons present in those shells.
Answer:
Explanation:
The BOHR MODEL has an atomic consisting of a small positively charged nucleus orbited by negatively charged electron. here's a closer look at the bohr model which is sometimes called the RUTHERFORD BOHR MODEL.
niels bohr proposed the bohr model of the atom in 1915. the model number of atom is based on the quantum mechanics. the model contains some errors, but it is important because it describes most of the accepted features of atomic theory without all the levels of the modern vision. unlike earlier model bohr model explain the RYDBERG formula for the special emission lines of atomic hydrogen.
main points of bohr model》》
1. electrons Orbits the nucleus in Orbit that have a set size and energy.
2. the energy of the orbit is related to its size .the lowest energy is found in the smallest Orbit.
3. radiations is observed or emitted when an electron move from one Orbit to another.
problems of bohr model》》
1. it violates the Heisenberg Uncertainty Principle because its consider electron to have both are known radius and Orbit.
2. the bohr model provides an incorrect value for the ground state orbital angular momentum.
3. It make poor predictions regarding the specta of large atoms.
4. it does not predict the relative intensities of spectral lines.
5. it does not explain the zeeman effect.