Question

Write down the drawbacks or bohr atomic modle??

Answer 1

Answer:

Bohr's model of atom, or theory of atom was devolped by Danish physicist named as Neil's Bohr in year 1913.

Bohr's theory -:

• Electrons revolve around the nucleus in circular orbits with attraction that's provided by electrostatic force.

• We know there are 7 orbits and Bohr said that the electron move only in some specific permissible orbits.

• These orbits are associated with a fixed amount of energy. That's why we call these orbits as *shells* or *energy level* or even *stationary states*.

Energy levels are classified by the letters K , L , M , N , O etc

The first orbit (K one) is nearest to the nucleus and has the lowest energy.

Sequence of shells according to their energy levels -

K < L < M < N < O

When the electron is at the lowest energy level, it is said to be at ground state.

And when it is at the highest energy level, it is said to be at excited state.

• Energy level of an electron remains constant in a particular Orbit as long as it revolves in the allowed shell.

• When an electrons moves from lower energy level to higher one, it absorbed energy and when it moves from higher energy level to lower energy level, it loses energy, energy is emitted.

Energy obtained or emitted is equal to Difference between two energy levels.

When an electron makes a transition from one orbit to another, energy is lost or gained in some discrete packets known as photon or quantum.

Limitations of Bohr's theory of atom -

•It don't explain about energy of an atom and it's stability.

• Heisnberg principle - Position and momentum of a particle cannot be determined at same time, accurately. Result of both of them is greater than h/4π

But according to Neil Bohr's theory, position and momentum is determined at same time (we know the radius and orbit of the electron).

It contradicts Heisnberg's principal.

• His theory was correct for small sized atoms but not for larged sized ones. His theory didn't tell electron orbits of large sized atoms.

• According to Bohr's theory, orbits were circular but now we know that they are 3-D and not 2-D.

• His theory does not explain anything about Zeeman (magnetic field) and stark (electric field) effect.

• His theory did explain about nucleus having one electron but not about Nucleus who is having more than one electron (multi-electronic atoms).

That's all! Maybe I missed one or two.