Periodic Classification and Periodic Properties 2 Question 46
46. Explain the following :
“The first ionisation energy of carbon atom is greater than that of boron atom whereas, the reverse is true for the second ionisation energy.”
(1989, 2M)
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Solution:
- The first ionisation energy of carbon is greater than the same of boron as predicted from periodic trend. However, for 2nd
ionisation trend is reversed due to stability of completely filled $2 s$-orbital of $\mathrm{B}^{+}$:
