Chapter 4 - Atoms and Elements - Exercises - Problems - Page 123: 82

$Ion: F^{-}$ $Ion: N^{3-}$ $Ion: Mg^{2+}$ $Ion: Na^{+}$

Since $Fluorine$ is in group 7 and a non-metal, it will gain one electron to obtain a full octet so it becomes $F^{-}$. Since $N$ is in group 5 (and a non-metal), it will gain three electrons to obtain a full octet so it becomes $N^{3-}$. Since $Magnesium$ is in group 2 and a metal, it will lose two electrons to obtain a full octet so it becomes $Mg^{2+}$. Since $Sodium$ is in group 1 and a metal, it will lose one electron to become stable so it becomes $Na^{+}$.