We are being asked to determine the smallest effective nuclear charge among elements 1-18 using the equation Zeff = Z – S.
Effective Nuclear Charge (Zeff) measures the force exerted onto an electron by the nucleus and can be calculated using Slater’s Rules
Z is the nuclear charge or atomic number
S is the shielding constant.
For this problem, we need to do the following steps.
Step 1: Determine the atomic number.
Step 2: Determine the electron configuration and group them by n-values.
Step 3: Calculate for the shielding constant using Slater's Rules.
Recall: The shielding constant can be calculated using Slater’s Rules:
For ns and np electrons:
1. Each electron in the same group will contribute 0.35 to the S value. A 1s electron contributes 0.30 to the S value of another 1s electron.
2. Each electron in the n–1 group contributes 0.85 to the S value.
3. Each electron in the n–2 or greater group contributes 1.00 to the S value.
Step 4: Calculate for Zeff.