Effective nuclear charge

[ATingin_3I]

Is it true that the effective nuclear charge felt by an electron in the outermost shell of an atom is equal to the group # found on the periodic table? If so, why is this? And is this a reliable "trick" we can use?

[DarrenKim_1H]

Hi Anna,

I believe what you are referring to is Slater's rule and it allow you to estimate the effective nuclear charge from the real number of protons in the nucleus and the effective shielding of electrons in each orbital "shell."

[Brian Tangsombatvisit 1C]

I'm not sure how to exactly calculate the effective nuclear charge felt by an electron when there's electron shielding. Professor Lavelle said in lecture that the outer electrons feel a reduced electrostatic attraction to the nucleus, resulting in an effective nuclear charge. It's not quite clear how to calculate this reduced charge, but I would say just know that there is a reduced charge as a result of the inner electrons shielding the outer electrons.

The formula to calculate the Zeff is probably not within the scope of this class, otherwise Professor Lavelle would have given the formula to us in lecture.

[Paul Hage 2G]

The effective nuclear charge felt by an electron in the outermost shell of an atom would be equal to the atomic number minus the number of shielding electrons (core electrons, not including valence electrons). Hope that helps.