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Explain atomic radius of elements of boron family.
Solution
On moving down the group, for each successive member one extra shell of electrons is added and, therefore, atomic radius is expected to increase.
However, a deviation can be seen. Atomic radius of $Ga$ is less than that of Al. This can be understood from the variation in the inner core of the electronic configuration.
The presence of additional $10 d$-electrons offer only poor screening effect for the outer
electrons from the increased nuclear charge in gallium. Consequently, the atomic radius of gallium ($135 pm$) is less than that of aluminium ($143 pm$).
However, regular periodicity is observed in case of ionic radius.
Similar Questions
Match List $I$ with List $II$. Choose the correct answer from the options given below:
| List $-I$ | List $-II$ |
|
$A.$ Melting point $[\mathrm{K}]$ |
$I.$ $\mathrm{Tl}>\mathrm{In}>\mathrm{Ga}>\mathrm{Al}>\mathrm{B}$ |
|
$B.$ Ionic Radius $\left[\mathrm{M}^{+3} / \mathrm{pm}\right]$ |
$II.$ $\mathrm{B}>\mathrm{Tl}>\mathrm{Al} \approx \mathrm{Ga}>\mathrm{In}$ |
| $C.$ $\Delta_{\mathrm{i}} \mathrm{H}_1 $ $ [\mathrm{~kJ} \mathrm{~mol}^{-1}]$ | $III.$ $\mathrm{Tl}>\mathrm{In}>\mathrm{Al}>\mathrm{Ga}>\mathrm{B}$ |
| $D.$ Atomic Radius $[pm]$ | $IV.$ $\mathrm{B}>\mathrm{Al}>\mathrm{Tl}>\mathrm{In}>\mathrm{Ga}$ |
