Quantum Mechanical Model of Atom
Bohr Theory give idea about atom, however, the Theory has some major shortcoming. Bohr Theory give explanation about energies transmission of electron in the hydrogen, and hydrogen like atoms, but fail to explain that of atom having more than one electron, even the hydrogen that have only one electron, the theory could not give explanation of the different spectral line intensities.
As such Quantum mechanics give theory known as wave mechanic that is more sophisticated than Bohr Theory, these theory can provide answer to what Bohr did not, and further more give explanation about spectral line intensities of atom with one electron, and for example wave mechanic can give full explanation of energy and spectra line of hydrogen. More also wave mechanic can be used to explain atoms with more than one electrons.
Base on the explanation above we can observe that wave quantum mechanics can be used to explain energy and properties and also explain the properties of atom with more than one electron, as such Quantum mechanics can be define as the branch of science that has ability to explain the dual behaviors of matter. Quantum mechanics is a theoretical science that focus on the study of microscopic motion of an objects with visible wave-likes and particle-like properties. This branch of science is independently developed by the following different scientist, Erwin Schrodinger, Heisenberg, Louis de Broglie and Werner.
Quantum mechanical model was developed on the basis of quantum theory, that say matter also have associated wave properties. According to quantum theory is not possible to know the position and momentum of an electron at the sometime, if possible that the position of electron is known, them the momentum is unknown, and if possible that the momentum of an electron is known, then the position is unknown, this variation of position of electron ant it momentum, give rise to principle known as Uncertainty Principle
Also quantum mechanical model of atom use complex shape of orbital, sometimes known as electron clouds, this model explain the probability where electron could found in space. As such this model is based on probability rather than that of certainty, the explanation is that the model is not sure of where electron is, but provide a volume of space where if search electron could be seen there.
Now major different between Bohr Theory and Quantum mechanics is that Bohr Theory provide that electron circling round the nucleus in a fixed orbit, just like how planet move round the sun. Whereas Wave mechanical model, is influence by Heisenberg uncertainty principle, hold that electron did not move round the nucleus in a fixed orbit. As such disagree with Bohr by saying that is not possible to know the position and momentum of electron at the same times, as such wave mechanics use Schrodinger equation to predict where the electron may be at any given time without knowing the exact position, this model is based on probability.
There are other difference, such as difference in the shape of electron orbits/atomic orbitals; inability of Bohr model to account for hybrid orbitals, molecular orbital resonance etc. but the major different is that Bohr model claim to know the exact path which electron travels, while wave mechanic did not claim to know where the electron is at any given time, but only can predict where electron can be found.