The energy of an electron in a single electron atom is determined through the principal of quantum number.
The order in which the energy of the various orbitals increases is 1s < 2s = 2p < 3s = 3p = 3d <4s = 4p = 4d= 4
Explanation:
The factor that affect the survival of the electron in the same orbit in the ground state of an atom are:
For a given value of the principal quantum number, the s orbital electron will be more tightly bound to the nucleus than p orbital electron, which is more tightly bound in comparison to a d orbital electron.
s orbital electrons will have a lesser amount of energy (more negative) than that of p orbital electrons which will have lesser energy than that of d orbital electrons.
The energy of orbitals depends upon the values of both principal quantum number (n) and azimuthal quantum number (l). Hence, the lower the value of (n + l) for an orbital, the lower is its energy. For the cases where we have two orbitals having the same value of (n + l), the orbital with a lower value of n (principal quantum number) will have the lower energy.
The energy of the orbitals in the same subshell decreases with increase in the atomic number (Zeff).
