Question

Compare $Li$ and $Be$ according to their $(IE{)}_2$ :

• A. $Li>Be$
• B. $Li<Be$
• C. $Li=Be$
• D. None of these

Answer 1

The correct option is A $Li>Be$

Electronic configuration of $Li$ is $1s^{2}2s^1$ so $(IE{)}_2$ we have to remove the second electron present in $1s$ shell which is completely filled and stable so it requires more energy to remove an electron from $1s$ shell of $Li$
Electronic configuration of $Be$ is $1s^{2}2s^2$ so $(IE{)}_2$ we have to remove the second electron present in $2s$ shell which is partially filled hence it requires less energy to remove an electron from $2s$ shell of $Be$ when compared with $Li$ so $(IE{)}_2$ of $Li$ is greater than $Be$. Hence option A is correct.