Question #39125

1 Answer
Jun 9, 2017

Answer:

Because M shell has the capacity for #8# electrons. Secondly, #18#
is used for all the sub shells in the M shell.

Explanation:

M shell has the capacity to store #8# electrons.
We have divided #18# in three sub shells of the shell M ,e.g.,
#3s = 2#
#3p = 6#
#3d = 10#
Now add them,
#2+6+10# = #18#
Electronic configuration of #Ca# =
#1s^2, 2s^2,2p^6, 3s^2,3p^6, 4s^2#, where;
#K = 2#
#L = 8#
#M = 8#
#N = 2#

You can take #18# as a whole but, if you'll take the M shell it contains 8 electrons, if we'll also count its sub shell electro configuration then it will be greater than 8.