Question

What is effective nuclear charge of S2- and S? Does the Zeff differs from ions and atoms of the same element.

Answer 1

Answer: The effective nuclear charge of $S^{2-}$ ion is less than the effective nuclear charge of S atom.

Explanation:

Effective nuclear charge is defined as the attraction of the protons present in the nucleus of an atom to the outermost electrons.

For ions, the effective nuclear charge changes than the neutral atom.

There are two types of ions:

• Cations: They are formed when an atom looses its valence electrons. They are positive ions.
• Anions: They are formed when an atom gain electrons in its outermost shell. They are negative ions.

For positive ions, the removal of electron increases the nuclear charge for an outermost electron because the outermost electrons are more strongly attracted by the nucleus. So, the effective nuclear charge increases for cations.

For negative ions, the addition of electron decreases the nuclear charge for an outermost electron because the outermost electrons are less strongly attracted by the nucleus. So, the effective nuclear charge decreases for anions.

Hence, the effective nuclear charge of $S^{2-}$ ion is less than the effective nuclear charge of S atom.

Answer 2

Effective nuclear charge is an estimate of the charge experienced by the valence electrons.
Sulfur has 6 valence electrons and a charge of 6+.
The 3s electrons in sulfur are the 3p electrons, because the former spend more time closer to the nucleus.
Using Slater's Rules, effective nuclear charge of sulfur is +5.5.

2) No! The Zeff doesn't differ from ions and atoms of the same element.