The region where this probability density function reduces to zero is called nodal surfaces or simply nodes .
Radial nodes : Radial nodes occur when the probability density of wave function for the electron is zero on a spherical surface of a particular radius . Number of radial nodes = n – l – 1
Angular nodes : Angular nodes occur when the probability density wave function for the electron is zero along the directions specified by a particular range . Number of angular nodes = l
Total number of nodes = n – 1
Degenerate orbitals : Orbitals having the same energy are called degenerate orbitals .
Shape of p and d-orbitals
Shielding effect or screening effect : Due to the presence of electrons in the inner shells , the electron in the outer shell will not experience the full positive charge on the nucleus .
So , due to the screening effect , the net positive charge experienced by the electron from the nucleus is lowered and is known as effective nuclear charge . Effective nuclear charge experienced by the orbital decreases with increase of azimuthal quantum number ( l ).
Aufbau Principle : In the ground state of the atoms , the orbitals are filled in order of their increasing energies
n + l rule-Orbitals with lower value of ( n + l ) have lower energy . If two orbitals have the same value of ( n + l ) then orbital with lower value of n will have lower energy .
The order in which the orbitals are filled is as follows :
1s , 2s , 2p , 3s , 3p , 4s , 3d , 4p , 5s , 4d , 5p , 4f , 5d , 6p , 7s ...