In calculating the x-ray energy levels the effective charge of the nucleus is taken to be Z - b, where Z is the atomic number.The parameter b enters because:
A)an electron is removed from the inner shell
B)a proton is removed from the nucleus
C)the quantum mechanical force between two charges is less than the classical force
D)the nucleus is screened by electrons
E)the Pauli exclusion principle must be obeyed

Question

Quizplus · Accepted Answer

The parameter b enters because the positively charged nucleus is screened by the negatively charged electrons in the atom, which reduces the effective nuclear charge experienced by the outermost electrons. This is known as electron shielding or screening. Therefore, the effective nuclear charge is taken to be Z - b.

In Calculating the X-Ray Energy Levels the Effective Charge of the Nucleus