The element X in group 17 has 3 shells, if so,
a) Write the subshells electronic configuration of the element.1. Element X belongs to group 17 means that it has 7 valence electrons. It has 3 shells that are K, L, M. The general electron configuration is 2, 8, 7. The subshell electronic configuration is 1s2, 2s22p6, 3s23p5. [1.0 Mark]
2. As it has 3 shells that means it belongs to 3rd period. [1. 0 Mark]