Effective Nuclear Charge (zeff)
Mediumchemistry
Effective nuclear charge (Zeff) generally:
Select the correct option:
Solution
Incorrect! Answer:
Increases across a period
- Definition: Zeff=Z−S, donde Z is actual nuclear charge and S is the shielding constant.
- Mechanical view: Moving across a period, one proton is added for each step. Simultaneously, one electron is added to the valence shell.
- Shielding efficiency: Shielding by electrons in the same shell is very poor. Most shielding comes from inner core electrons.
- Core Shielding: As we move across a period, the number of core (inner) electrons remains constant.
- Net Effect: The increasing nuclear charge (Z) is not fully compensated by the added valence electrons. Thus, valence electrons feel a progressively stronger pull. Zeff increases.
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About This Question
- Subject
- chemistry
- Chapter
- classification of elements and periodicity in properties
- Topic
- effective nuclear charge (zeff)
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
Increases across a period
- Definition: Zeff=Z−S, donde Z is actual nuclear charge and S is the shielding constant.
- Mechanical view: Moving across a period, one proton is added for each step. Simultaneously, one electron is added to the valence shell.
- Shielding efficiency: Shielding by electrons in the same shell is very poor. Most shielding comes from inner core electrons.
- Core Shielding: As we move across a period, the number of core (inner) electrons remains constant.
- Net Effect: The increasing nuclear charge (Z) is not fully compensated by the added valence electrons. Thus, valence electrons feel a progressively stronger pull. Zeff increases.
This medium difficulty chemistry question is from the chapter classification of elements and periodicity in properties, covering the topic of effective nuclear charge (zeff). It appeared in the 2025 exam.
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