Advertisements
Advertisements
प्रश्न
Answer in brief.
State the postulates of Bohr’s atomic model.
Advertisements
उत्तर
The postulates of Bohr's atomic model (for the hydrogen atom):
- The electrons revolve around the nucleus in circular orbits. This is the same assumption as in Rutherford’s model and the centripetal force necessary for the circular motion is provided by the electrostatic force of attraction between the electron and the nucleus.
- The radius of the orbit of an electron can only take certain fixed values such that the angular momentum of the electron in these orbits is an integral multiple of `"h"/(2π)`, h being Planck’s constant. Such orbits are called stable orbits or stable states of the electrons and electrons in these orbits do not emit radiation as is demanded by classical physics. Thus, different orbits have different and definite values of angular momentum and therefore, different values of energy.
- An electron can make a transition from one of its orbits to another orbit having lower energy. In doing so, it emits a photon of energy equal to the difference in its energies in the two orbits.
APPEARS IN
संबंधित प्रश्न
Derive the expression for the energy of an electron in the atom.
The radii of Bohr orbit are directly proportional to ______
What is the energy of an electron in a hydrogen atom for n = ∞?
Starting with 𝑟 = `(ε_0h^2n^2)/(pimZe^2),` Show that the speed of an electron in nth orbit varies inversely to principal quantum number.
State any two limitations of Bohr’s model for the hydrogen atoms.
The magnifying power of a telescope is high, if its objective and eyepiece have respectively ____________.
Bohr model is applied to a particle of mass 'm' and charge 'q' is moving in a plane under the influence of a transverse magnetic field 'B. The energy of the charged particle in the nth level will be (h = Planck's constant).
The ratio of the velocity of the electron in the first orbit to that in the second orbit is ____________.
How many moles of electrons are required for reduction of 9 moles of Cr3+ to Cr?
If the ionisation potential of helium atom is 24.6 volt, the energy required to ionise it will be ____________.
In Bohr's model of hydrogen atom, the period of revolution of the electron in any orbit is proportional to ______.
The binding energy of an electron in nth orbit of the hydrogen atom is given by `"E"_"n" = 13.6/"n"^2 "eV."` The energy required to knock an electron from the second orbit in eV will be ____________.
In hydrogen emission spectrum, for any series, the principal quantum number is n. Corresponding maximum wavelength λ is ______.
(R = Rydberg's constant)
In hydrogen spectnun, the wavelengths of light emited in a series of spectral lines is given by the equation `1/lambda = "R"(1/3^2 - 1/"n"^2)`, where n = 4, 5, 6 .... And 'R' is Rydberg's constant.
Identify the series and wavelenth region.
Angular speed of an electron in the ground state of hydrogen atom is 4 × 1016 rad/s. What is its angular speed in 4th orbit?
In Bohr model, speed of electron in nth orbit of hydrogen atom is ______. (b = Planck's constant, n = principal quantum number, ∈0 is the permittivity of free space, e = electronic charge)
The minimum energy required to excite a hydrogen atom from its ground state is ____________.
Using Bohr's quantization condition, what is the rotational energy in the second orbit for a diatomic molecule. (I = moment of inertia of diatomic molecule, h = Planck's constant)
The de-Broglie wavelength of an electron in 4th orbit is ______.
(r = radius of 1st orbit)
In any Bohr orbit of hydrogen atom, the ratio of K.E to P.E of revolving electron at a distance 'r' from the nucleus is ______.
The radius of orbit of an electron in hydrogen atom in its ground state is 5.3 x 10-11 m After collision with an electron, it is found to have a radius of 13.25 x 10-10 m. The principal quantum number n of the final state of the atom is ______.
The ground state energy of the hydrogen atom is -13.6 eV. The kinetic and potential energy of the electron in the second excited state is respectively ______
An electron of mass m and charge e initially at rest gets accelerated by a constant electric field E. The rate of change of de-Broglie wavelength of this electron at time t ignoring relativistic effects is ______.
Which of the following series of transition of hydrogen spectrum falls in visible region?
Ultraviolet light of wavelength 300 nm and intensity 1.0 Wm−2 falls on the surface of a photosensitive material. If one percent of the incident photons produce photoelectrons, then the number of photoelectrons emitted from an area of 1.0 cm2 of the surface is nearly ______.
Find the ratio of radius of 1st Bohr orbit to that of 4th Bohr orbit.
