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...