describe the relationship between an element's placement in the periodic table and the number of electrons in its outermost energy level

Answer 1

The name for the electrons on the outer-most energy level is referred to as valence electrons. When talking about the Group A (Groups 1,2, and 13-18) elements, they increase from left-to-right across the periodic table. These generally don't apply to Group B (groups 3-12), or transition metals. Also, it is key to note Helium, which is on the far right in Group 8A (18),has only 2 valence electrons.