Explain the electronic configuration of Sodium (Na) and how this relates to its position in the periodic table.

Firstly we must use the periodic table to look at the number of protons (11) contained within a sodium atom. This tells us how many electrons are contained within the shells of that atom as these two are always equal in neutral atoms (11). Next we need to remember how many electrons each energy level can hold (1st:2, 2nd:8, 3rd:8, 4th:18). We must then simply work up through the shells adding the electrons until each energy level is full and stopping once we have used all of the electrons for that atom. (2:8:1)
Interestingly, the number of energy levels an atom of an element possesses tells us which row in the Periodic Table it sits. And the number of electrons in its outer shell tells us which group(column) it is in. Thus Na sits in the 1st group on the third row.