Principal quantum number (n)

Principal quantum number (n):

This quantum number represents the main energy level or energy shell in which the electron is present. It is represented by n and can have values = 1, 2, 3, etc. Since each energy level is associated with a definite amount of energy, this quantum number determines to a large extent the energy of an electron. It also determines the average distance of an electron from the nucleus. As the value of n increases, the electron gets farther away from the nucleus and its energy increases. This is because the electrostatic energy of attraction is inversely proportional to the distance of the electron from the nucleus and it has a negative sign.