Effective Nuclear Charge from Allred Rochow's Electronegativity Calculator

Formula Used:

\[ Z = \frac{X_{A.R} \times r_{covalent} \times r_{covalent}}{0.359} \]

Effective Nuclear Charge:

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1. What is Effective Nuclear Charge from Allred-Rochow's Electronegativity?

Definition: This calculator estimates the effective nuclear charge experienced by electrons in an atom using Allred-Rochow's electronegativity scale and covalent radius.

Purpose: It helps chemists and physicists understand the attractive force between the nucleus and electrons in polyelectronic atoms.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Z = \frac{X_{A.R} \times r_{covalent}^2}{0.359} \]

Where:

\( Z \) — Effective nuclear charge
\( X_{A.R} \) — Allred-Rochow's electronegativity value
\( r_{covalent} \) — Covalent radius (in Ångströms)

Explanation: The formula relates electronegativity to the effective nuclear charge through the covalent radius of the atom.

3. Importance of Effective Nuclear Charge

Details: Effective nuclear charge helps explain periodic trends like atomic size, ionization energy, and chemical reactivity.

4. Using the Calculator

Tips: Enter the Allred-Rochow's electronegativity value and covalent radius (in Å). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is Allred-Rochow's electronegativity?
A: It's an electronegativity scale that relates to the charge experienced by an electron on the "surface" of an atom.

Q2: How is covalent radius measured?
A: Covalent radius is half the distance between two identical atoms joined by a single covalent bond, typically measured in Ångströms (1 Å = 10^-10 m).

Q3: Why is 0.359 used in the formula?
A: This is an empirical constant that relates the Allred-Rochow electronegativity to the effective nuclear charge.

Q4: What are typical values for Allred-Rochow electronegativity?
A: Values range from about 0.7 for cesium to 3.5 for fluorine on this scale.

Q5: How does effective nuclear charge vary across the periodic table?
A: It generally increases across a period and decreases down a group, following similar trends to electronegativity.