Question

1. How does the period (row) in which an element is located relate to the number of shells that contain electrons?

Answer 1

1. The period number tells us about the number of shells in an element(for example Na located in third period has three electron shells)

2. Group number tells us the amount of electrons present in the valence shell thus also tells us about the ionic charges they form

3. They all have a stable electronic configuration with complete valence shells hence they also don't form ions.