NCERT Class XI Chemistry Solutions

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Question : 35
Total: 40
Use molecular orbital theory to explain why Be2 molecule does not exist.
Solution:  
Beryllium atom has electronic configuration 1s22s2. So, in Be2 there are a total of eight electrons which must be filled in four molecular orbitals.
M.O. configuration of Be2σ1s2σ*1s2σ2s2σ*2s2
B.O. = 1/2(4 – 4) = 0. Since the bond order is zero it shows that molecular beryllium will not exist.
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