🤓 Based on our data, we think this question is relevant for Professor Briggs' class at ASU.

Among elements 1–18, which element or elements have the
smallest effective nuclear charge if we use the equation Z_{eff} = Z - S to calculate Z_{eff}?

We are being asked to determine the smallest effective nuclear charge among elements 1-18 using the equation Z_{eff} = Z – S.

Effective Nuclear Charge (Z_{eff}) measures the force exerted onto an electron by the nucleus and can be calculated using Slater’s Rules

$\overline{){{\mathbf{Z}}}_{{\mathbf{eff}}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}{\mathbf{Z}}{\mathbf{}}{\mathbf{-}}{\mathbf{}}{\mathbf{S}}}$

where:

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.