1. What is Effective Nuclear Charge?

Effective nuclear charge (Zeff) is the net positive charge experienced by an electron in a multi-electron atom. It accounts for both the attraction to the nucleus and repulsion from other electrons.

2. How Does the Calculator Work?

The calculator uses Slater's rules formula:

Where:

• \( Z \) — Atomic number (number of protons)
• \( \sigma \) — Shielding constant (calculated from Slater's rules)

Explanation: The shielding constant (σ) represents how much the other electrons shield the valence electrons from the full nuclear charge.

3. Importance of Zeff Calculation

Details: Zeff helps explain periodic trends like atomic size, ionization energy, and electronegativity. Higher Zeff means electrons are held more tightly.

4. Using the Calculator

Tips: Enter the atomic number (1-118) and the shielding constant calculated from Slater's rules. The shielding constant depends on the electron configuration.

5. Frequently Asked Questions (FAQ)

Q1: What are Slater's rules?
A: Empirical rules to estimate the shielding constant (σ) based on an electron's orbital type and the orbitals of other electrons.

Q2: How does Zeff vary across the periodic table?
A: Zeff increases across a period (left to right) and slightly increases down a group.

Q3: Why is Zeff important in chemistry?
A: It explains why valence electrons behave differently in different atoms, affecting chemical properties and reactivity.

Q4: What's the difference between Z and Zeff?
A: Z is the actual nuclear charge, while Zeff is the net charge experienced by an electron after accounting for shielding.

Q5: Can Zeff be measured experimentally?
A: Yes, through X-ray photoelectron spectroscopy (XPS) which measures electron binding energies.