The picture of atoms consisting of tiny dense nuclei surrounded by lighter and even tinier electrons continually moving about the nucleus was well established following the work of Ernest Rutherford and his colleagues in the early twentieth century.
The picture was called the planetary model because it pictured the atom as a miniature solar system with the electrons circling the nucleus.
The simplest atom is hydrogen, consisting of a single protons as the nucleus.
The distance between the two particles is what determines the force of attraction to the electron.
The force between two particles is the same as the force between two planets, but the force depends on the magnitudes of the charges on the particles.
It is convenient to work with potentials since they are forms of energy.
The Coulomb potential is also called the electrostatic potential.
Classical mechanics says that the equations of motion should be the same, with the electron moving around the nucleus in a circular or elliptical pattern.
These coordinates are similar to the ones used in gps devices and most smart phones that track positions on our spherical earth, with the two angular coordinates specified by the latitude and longitude, and the linear coordinate specified by sea-level elevation.
The classical hydrogen atom is constrained to lie in a plane like the planets because of the spherical symmetry of central potentials.
The classical mechanics description of the atom is incomplete since an electron moving in an elliptical path should emit radiation.
This loss in energy should cause the electron to get 888-282-0465 888-282-0465 888-282-0465 888-282-0465 888-282-0465 888-282-0465, implying that atoms are inherently unstable.
Classical electromagnetism's prediction that the electron in hydrogen would emit light was ignored by the physicist in 1913.
He incorporated the classical mechanics description of the atom into the ideas of quantization and Einstein.
If the electron moved to a different location, it would emit or absorb a photon.
The value of the energy difference is always positive.
Instead of allowing for continuous values, Bohr assumed that the only values that could occur were the ones that were quantized.
One of the fundamental laws of physics is that matter is most stable with the lowest possible energy.
It has the lowest energy in the 1 orbit.
The difference in energy is emitted as a photon when an electron transitions from an excited state to a less excited state.
If a photon is absorbed by an atom, the energy of the photon moves an electron from a lower energy to a more excited one.
The energy of electrons in atoms can be compared to what we know about energy.
The law says that we can't create or destroy energy.
If a certain amount of external energy is required to excite an electron from one energy level to another, that same amount of energy will be liberated when the electron returns to its initial state.
There is a second quantum.
Since the model only involved a single electron, it could be applied to the single electron ion He+, Li2+, Be3+, and so forth, which differ from hydrogen only in their nuclear charges, and so they are collectively referred to as hydrogen.
The ionization limit is where the electron is removed from the nucleus.
It became clear to most physicists at that time that the classical theories that worked so well in the macroscopic world were fundamentally flawed and could not be extended down into the microscopic domain.
The next simplest atom, He, which only has two electrons, was unable to be extended by Bohr's theory.
When a proper model of quantum mechanics was developed, it was found that the classical mechanics concept of precise orbits was not compatible with it.
When researchers were able to predict the energy of an electron at a certain distance from the nucleus, they were very excited.
The horizontal lines show the relative energy of the hydrogen atom, while the vertical arrows show the energy of the electrons as they move between the orbits.