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Definition: This calculator estimates the number of ions formed from one formula unit of a substance using the Kapustinskii approximation.
Purpose: It helps in crystallography and materials science to quickly estimate the number of ions based on the Madelung constant.
The calculator uses the formula:
Where:
Explanation: The Kapustinskii approximation relates the Madelung constant to the number of ions in the crystal structure.
Details: Knowing the number of ions helps in understanding crystal structures, calculating lattice energies, and predicting material properties.
Tips: Enter the Madelung constant for your crystal structure. The value must be > 0.
Q1: What is the Madelung constant?
A: The Madelung constant is used in determining the electrostatic potential of a single ion in a crystal by approximating the ions by point charges.
Q2: Why is 0.88 used in the formula?
A: This is an empirical factor derived from the Kapustinskii equation that relates the Madelung constant to the number of ions.
Q3: What's a typical Madelung constant value?
A: For NaCl structure it's ~1.748, for CsCl ~1.763, and for zincblende ~1.638.
Q4: Is this approximation accurate for all crystals?
A: It provides a reasonable estimate but may not be precise for all crystal structures.
Q5: Can I use this for molecular crystals?
A: No, this approximation is primarily for ionic crystals.