Effective Atomic Number (EAN) Calculator

Effective Atomic Number Formula:

\[ EAN = Z - \text{shielding electrons} \]

Effective Atomic Number (EAN):

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1. What is Effective Atomic Number?

The Effective Atomic Number (EAN) is a concept used in coordination chemistry to describe the total number of electrons surrounding the central metal atom in a complex, including those donated by ligands. It helps predict the stability of coordination compounds.

2. How Does the Calculator Work?

The calculator uses the EAN formula:

\[ EAN = Z - \text{shielding electrons} \]

Where:

\( Z \) — Atomic number of the central metal atom
Shielding electrons — Number of electrons not participating in bonding

Explanation: The EAN rule states that stable complexes often have an EAN equal to the atomic number of the next noble gas (2, 10, 18, 36, 54, or 86).

3. Importance of EAN Calculation

Details: Calculating EAN helps predict the stability of coordination compounds. Complexes with EAN values matching noble gas configurations are typically more stable (Sidgwick's EAN rule).

4. Using the Calculator

Tips: Enter the atomic number of the central metal atom and the number of shielding electrons (non-bonding electrons). Both values must be positive integers.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of EAN in coordination chemistry?
A: EAN helps predict the stability of coordination compounds. Complexes with EAN equal to the nearest noble gas atomic number are generally more stable.

Q2: How do I determine shielding electrons?
A: Shielding electrons are the non-bonding electrons of the metal ion. For example, in [Fe(CN)6]4-, Fe2+ has 6 shielding electrons (d6 configuration).

Q3: What is the 18-electron rule?
A: The 18-electron rule is a special case of the EAN concept where stable complexes often have 18 valence electrons (EAN = 36, like Kr).

Q4: Are there exceptions to the EAN rule?
A: Yes, many stable complexes don't obey the EAN rule perfectly, especially for early transition metals and certain coordination geometries.

Q5: How does EAN relate to oxidation state?
A: The oxidation state affects the number of shielding electrons. Higher oxidation states mean fewer shielding electrons, which affects the EAN calculation.