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

2. How does the group (column) in which an element is located relate to the number of valence electrons in its outer shell?

3. The elements in Group 18 are known as noble gases.

In terms of their electron configurations, what do the noble gases all have in common?

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.