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F has the highest electronegativity amon...

`F` has the highest electronegativity among the group `17` elements (i.e. `ns^(2) np^(2) np^(5)` type), on the Pauling scale, but the `EA` of `F` is less than that of `Cl` because

A

`F` being the first member of the family behaves in an unusual manner.

B

The atomic number of `F` is less than that of `Cl`.

C

`Cl` can accommodate an electron better than `F` by utilsing its vacant `3d` orbital.

D

Small size, high `EN` and an increased electron-electron replusion makes addition of an electron to `F` less favourable.

Text Solution

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The correct Answer is:
To understand why fluorine (F) has a lower electron affinity (EA) than chlorine (Cl) despite having the highest electronegativity among the group 17 elements, we can break down the explanation into several steps: ### Step-by-Step Solution: 1. **Definition of Electronegativity and Electron Affinity**: - Electronegativity is the tendency of an atom to attract shared electrons in a chemical bond. Fluorine has the highest electronegativity on the Pauling scale. - Electron affinity (EA) is the amount of energy released when an electron is added to a neutral atom to form a negative ion. 2. **Comparison of Electron Configurations**: - Fluorine has the electron configuration of 1s² 2s² 2p⁵, meaning it has 7 electrons in its outer shell and needs one more to complete its octet. - Chlorine has the electron configuration of 1s² 2s² 2p⁶ 3s² 3p⁵, with 7 electrons in its outer shell as well, but it is in a higher energy level (n=3). 3. **Size and Electron Repulsion**: - Fluorine is smaller in size compared to chlorine. The small size of fluorine leads to greater electron-electron repulsion when an additional electron is added to its already filled 2p subshell. - In contrast, chlorine, being larger, has more space in its 3p subshell to accommodate an additional electron, which reduces the electron-electron repulsion. 4. **Energy Considerations**: - The energy released when adding an electron to fluorine is less favorable due to the high electron-electron repulsion in the small 2p orbital. - Chlorine can accommodate the additional electron more easily, leading to a higher electron affinity. 5. **Conclusion**: - Therefore, despite fluorine having the highest electronegativity, its electron affinity is lower than that of chlorine because the small size of fluorine leads to increased electron-electron repulsion, making the addition of an electron less favorable. ### Final Answer: The reason that fluorine has a lower electron affinity than chlorine, despite having the highest electronegativity, is due to the small size of fluorine leading to increased electron-electron repulsion, which makes the addition of an electron less favorable.
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Fluorine has the highest electronegativity among the ns^(2) np^(5) group on the Pauling scale, but the elctron affinity of fluorine is less than that of chlorine because :

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Knowledge Check

  • If the valence shell electronic structure for an element is ns^(2) np^(5) , this element will belong to the group of

    A
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    B
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