effective nuclear charge (zeff)

Question

Effective nuclear charge (Zeff) generally:

RankGuru · Accepted Answer

1. **Definition**: $Z_{eff} = Z - S$, donde $Z$ is actual nuclear charge and $S$ is the shielding constant.
2. **Mechanical view**: Moving across a period, one proton is added for each step. Simultaneously, one electron is added to the valence shell.
3. **Shielding efficiency**: Shielding by electrons in the same shell is very poor. Most shielding comes from inner core electrons.
4. **Core Shielding**: As we move across a period, the number of core (inner) electrons remains **constant**.
5. **Net Effect**: The increasing nuclear charge ($Z$) is not fully compensated by the added valence electrons. Thus, valence electrons feel a progressively stronger pull. **$Z_{eff}$ increases**.

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effective nuclear charge (zeff)

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