What is the name of the species formed when a sodium atom loses an electron?

A sodium atom has one valence electron, since it is in Group 1 of the periodic table. If it loses this lone valence electron in its outermost shell, its electron configuration becomes similar to that of neon, which is just before it on the periodic table. If we remove one electron, the sodium atom will lose a negative charge, therefore giving it a positive net charge. Therefore, we call it an Na + ion.