Question

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The trend of metallic properties is not that obvious in group 17. Fluorine is the most electronegative element and has no basic properties. Iodine and Bromine dissolve in oleum and other strong oxidising solvents forming species like $[I_2{]}^{+}$ and $[B{r}_2{]}^{+}$. Many other species like $[I_3{]}^{+}$ and $[B{r}_3{]}^{+}$ have also been prepared.

The bond length in $[B{r}_2{]}^{+}$ ion is 2.15 $\stackrel{\circ }{A}$ whereas the bond length of $B{r}_2$ is 2.27 $\stackrel{\circ }{A}$. This shows:

• A. The electron is removed from a bonding orbital
• B. The electron is removed from an anti-bonding orbital
• C. The electron is shifted from a bonding to an anti-bonding orbital
• D. The electron is shifted from an anti-bonding to a bonding orbital

Answer 1

The correct option is B The electron is removed from an anti-bonding orbital

Since the bond length of $B{r}_2^{+}$ is lesser than that of $B{r}_2$, it means that the bond order of $B{r}_2^{+}$ is more than $B{r}_2$. This may be possible if an electron is removed from an anti-bonding orbital.