Class 11 NEET Chemistry Classification Of Elements And Periodicity In Properties

Li,Be,B,C - these elements belong to the same period. Generally the value of 1‌st ‌ ionisation potential increases in moving from left to right in a period, since the nuclear charge of the elements also increase in the same direction. But the ionisation potential of boron (B→2s22p1) is lower than that of beryllium (Be→2s2), since in case of boron, 2p1 electron has to be removed to get B+ while in case of Be (2s2)s -electron has to be removed to get Be+ (2s1)⋅p electron can be removed more easily than s electron so the energy required to remove electron will be less in case of boron. The order will be
Li<B<Be<C