Question

Why cant the electron configuration of calcium be 2,8,9,1

Answer 1

According to octet rule, a valence shell (outer shell) can only posses 8 electrons, giving it the same electronic configuration of the noble gas. So, electronic configuration of calcium is 2,8,8,2

Answer 2

Actually each shell is further divided into subshell, and each subshell contains a given number of orbitals.There are four different types of subshells - the s subshell, p subshell, d subshell and f subshell. Each subshell has a specific number of orbitals, and so can hold a given number of electrons. Another important point to note is that these orbitals are filled in the increasing order of energy. It is because of this order (in which the atomic orbitals are filled) that the electronic configuration of of calcium is 2, 8, 8, 2 and not 2, 8, 9, 1 or 2, 8, 10.


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