The ionic symbol for sodium is Na+. Sodium is a highly reactive metal that readily loses its single outer electron to form a positively charged ion, known as a cation. This electron loss results in the formation of the sodium ion, which has a stable electron configuration similar to that of the noble gas neon. The data supporting this is derived from the periodic table, where sodium is located in Group 1, indicating its tendency to lose one electron to achieve a full outer shell. This behavior is consistent with the general trend of metals in the periodic table, which is to lose electrons and form cations. The ionic symbol Na+ succinctly represents this process and the resulting sodium ion.