Question

why we write 8 electrons in 3 shell instead of 18 in arrangement of electrons in atoms . Chemistry

Answer 1

We do so, to make it stable. If we would put 18 electrons in the third shell, then it would be much difficult for the third shell to complete its octet.For better understanding lets take an example of calcium, its electronic configuration is 2,8,8,2. In this case we divide the last 10 electrons into 8 and 2 so that the outermost shell can complete its octet and can transfer 2 electrons easily.In the case of calcium if we would do its confriguration as 2,8,10 then now bcoz there are 10 electrons in its outermostshell, the transfer of electrons would become much difficult and also its octet would not be completed.

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