1. What is Effective Nuclear Charge?

Definition: The Effective Nuclear Charge is the net positive charge experienced by an electron in a polyelectronic atom.

Purpose: It helps understand how strongly an electron is attracted to the nucleus, accounting for shielding by other electrons.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Z_{eff} \) — Effective nuclear charge
• \( Z \) — Atomic number (number of protons)
• \( \sigma \) — Shielding constant (measure of electron shielding)

Explanation: The shielding constant represents how much the nuclear charge is reduced by intervening electrons.

3. Importance of Effective Nuclear Charge

Details: Effective nuclear charge explains periodic trends like atomic size, ionization energy, and electronegativity.

4. Using the Calculator

Tips: Enter the atomic number (must be ≥ 1) and shielding constant (must be ≥ 0). The shielding constant is typically between 0 and Z-1.

5. Frequently Asked Questions (FAQ)

Q1: What is the shielding constant?
A: The shielding constant (σ) measures how much an electron is shielded from the nucleus by other electrons.

Q2: How do I determine the shielding constant?
A: It can be calculated using Slater's rules or obtained from experimental data like NMR spectroscopy.

Q3: What's the range for effective nuclear charge?
A: Z_eff ranges from just above 0 (for outer electrons) up to Z (for the 1s electron in hydrogen).

Q4: Why does effective nuclear charge increase across a period?
A: While Z increases, shielding increases more slowly, so Z_eff increases left to right.

Q5: How does effective nuclear charge affect atomic radius?
A: Higher Z_eff pulls electrons closer, decreasing atomic radius.