Cations

A neutral sodium atom is likely to achieve an octet in its outermost shell by losing its one valence electron.

The cation produced in this way, Na⁺, is called the sodium ion to distinguish it from the element. The outermost shell of the sodium ion is the second electron shell, which has eight electrons in it. The octet rule has been satisfied. Figure 1 is a graphical depiction of this process.

Figure 1 : The Formation of a Sodium Ion. On the left, a sodium atom has 11 electrons. On the right, the sodium ion only has 10 electrons and a 1+ charge.