Question

Describe the process for determining the orbital diagram for an atom, including the number of orbitals and electrons for each subshell. Describe how quantum numbers relate to the orbital diagrams. How does this quantum mechanical view of the atom differ from the Bohr model of the atom?

Answer 1

The orbital diagram is constructed by using following three principles,

1) Aufbau principle : - It states that the electrons are filled in orbital having lower in energy. The energy is determined by summing the quntum number & azimutham Q.N.eg .energy 1s orbitalis 1 + 0 = 1, 5d orbital= 5 + 2=7 etc.

2) Poulis Exclusion principle : -  In an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins. This means if one is assigned an up-spin ( +1/2), the other must be down-spin (-1/2).

3) Hunds rule which  states that the lowest energy atomic state is the one that maximizes the sum of the S values for all of the electrons in the open subshell.

The quantum number are ralated with energy of orbital.

Difference in Bohr midel & Quantum mechanical model : -

The major difference is that in the Bohr model the electrons revolve around the nucleus in fixed orbits similar to the way planets orbit around the sun. The wave mechanical model, influenced by the Heisenberg uncertainty principle, says that electrons do not orbit in fixed orbits. In fact, it is impossible to know both the position and momentum of a particle like an electron. Instead the wave mechanical model uses the Schroedinger equation to predict the probabilities of where the electron may be positioned at any given time (without saying with any certainty where the electron actually is).