Question

In $3d$ transition series, if nuclear charge increases, the screening effect:

• A. increases
• B. decreases
• C. first decreases and then increases
• D. first increases and then decreases

Answer 1

Answer: (A)

increases

The effective nuclear charge is the net positive charge experienced by an electron in a multi-electron atom. The term "effective" is used because the shielding effect of negatively charged electrons prevents higher orbital electrons from experiencing the full nuclear charge.

The effective nuclear charge on an electron is given by: $Zeff=Z-S$

Where $Z$ is the number of protons in the nucleus (atomic number), and $S$ is the number of electrons between the nucleus and the electron.

Sheilding effect:

Electrons in an atom can shield each other from the pull of the nucleus. This effect, called the shielding effect, describes the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell. More the electron shells, greater is the shielding effect experienced by the outermost electrons.