## Category: Atoms

## If Bohr’s quantisation postulate (angular momentum nh/2n) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why then do we never speak of quantisation of orbits of planets around the sun?

## The total energy of an electron in the first excited state of the hydrogen atom is about -3.4 eV. (a) What is the kinetic energy of the electron in this state?

The total energy of an electron in the first excited state of the hydrogen atom is about -3.4 eV. (a) What is the kinetic energy of the electron in this state? (b) What is the potential energy of the electron Read More …

## Classically, an electron can be in any orbit around the nucleus of an atom. Then what determines the typical atomic size? Why is an atom not, say, thousand times bigger than its typical Size? The question had greatly puzzled Bohr before he arrived at his famous model of the atom that you have learnt in the text. To simulate what he might well have done before his discovery, let us play as follows with the basic constants of nature and see if we can get a quantity with the dimensions of length that is roughly equal to the known size of an atom ( 10-10 m).

Classically, an electron can be in any orbit around the nucleus of an atom. Then what determines the typical atomic size? Why is an atom not, say, thousand times bigger than its typical Size? The question had greatly puzzled Bohr before Read More …

## Obtain an expression for the frequency of radiation emitted when a hydrogen atom de-excites from level n to level (n-l). For large n, show that this frequency equals the classical frequency of revolution of the electron in the Orbit.

## The gravitational attraction between electron and proton in a hydrogen atom is weaker than the coulomb attraction by a factor of about 10-40. An alternative way of looking at this fact is to estimate the radius of the first Bohr Orbit of a hydrogen atom if the electron and proton were bound by gravitational attraction. You will find the answer interesting.

The gravitational attraction between electron and proton in a hydrogen atom is weaker than the coulomb attraction by a factor of about 10-40. An alternative way of looking at this fact is to estimate the radius of the first Bohr Orbit of Read More …

## Answer the following questions, which help you understand the difference between Thomson’s model and Rutherford’s model better.

Answer the following questions, which help you understand the difference between Thomson’s model and Rutherford’s model better. (a) Is the average angle of deflection of a -particles by a thin gold foil predicted by Thomson’s model much less, about the same, or Read More …