Among elements 1-18, which element or elements have the smallest effective nuclear charge if we use the equation zeff=z-s to calculate zeff? check all that apply.

Slater’s Rules can be used for calculating the effective nuclear charge (Z eff)

The effective nuclear charge is given by the formula

Zeff = Z - S

Where Z is the actual nuclear charge and S is the shielding constant

The value of shielding constant can be determined using the following rules

Rule 1

Write the electronic configuration in the following order

(1s) (2s, 2p) (3s, 3p) (3d) (4s, 4p) (4d) (4f) (5s, 5p) ...

Rule 2. Identify the group of the electron whose effective nuclear charge is to be determined. Ignore all the electrons to the right side of this group

Rule 3. if the electron under consideration is an ‘s’ or ‘p’ orbital, then all other electrons in the same group (ns, np) contributes 0.35 to the shielding constant (S), and all the electrons in the (n - 1) shell contribute 0.85 to the shielding constant. All the other electrons to the left of (n-1) shell contributes a value of 1.00 to the shielding constant.

Rule 4. If the electron under consideration is in ‘d’ or ‘f’ orbital, each additional electrons in the same group contributes 0.35 to shielding constant. All the other electrons to the left contributes 1.00 to shielding constant.

If we use this rule to calculate Zeff of Hydrogen,

H = (1S¹)

Z=1

S=0

Zeff = Z - S = 1-0 = 1, which is the smallest Zeff possible.

Smallest Zeff is shown by Hydrogen