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The p-Block Elements — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryThe p-Block Elements2 Marks
Question
Explain why $NH_3$ is basic while $BiH_3$ is only feebly basic.
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Answer

Nitrogen has a small size due to which the lone pair of electrons is concentrated in a small, region. This means that the charge density per unit volume is high. On moving down a group, the size of the central atom increases and the charge gets distributed over a large area decreasing the electron density. Hence, the electron donating capacity of group $15$ element hydrides decreases on moving down the group.

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