What is the main difference between Bohr's model of the atom and the atomic theory that is currently accepted?

1 Answer
May 6, 2016

Answer:

#color(green)("Electrons do not move around the nucleus in circular orbits")#.

Explanation:

Bohr developed a quantum model for the hydrogen atom. The Bohr model was based on the following assumptions.

  • The electron in a hydrogen atom travels around the nucleus in a circular orbit.
  • The energy of the electron in an orbit is proportional to its distance from the nucleus. The further the electron is from the nucleus, the more energy it has.
  • Only a limited number of orbits with certain energies are allowed. In other words, the orbits are quantized.
  • Light is absorbed when an electron jumps to a higher energy orbit and emitted when an electron falls into a lower energy orbit.
  • The energy of the light emitted or absorbed is exactly equal to the difference between the energies of the orbits.

He derived an equation to determine the energy levels available to the electron in the hydrogen atom:

#E=-2.178xx10^(-18)J(Z^2)/(n^2)#

Where #n# is an integer (the value of n determines the energy level of the electron) and #Z# is the nuclear charge.

The negative sign means that the energy of the electron bound to the nucleus is lower than it would be if the electron were at an infinite distance where the energy is zero.

In the hydrogen atom, if the electron is in the first level, it would have the lowest possible energy called the ground state.

The energy levels calculated by Bohr closely agreed with the values obtained from the hydrogen emission spectrum. When applied to atoms other than hydrogen, Bohr's model did not work.

In fact, Bohr's model is an incorrect model for the hydrogen atom. #color(green)("Electrons do not move around the nucleus in circular orbits")#.

The Bohr Model