Metallic atoms with few valence electrons tend to give out electrons in electrovalency because they are more stable when they have a full outer shell of electrons. This is due to the fact that the energy required to remove an electron from a full outer shell is much higher than the energy required to remove an electron from an incomplete outer shell. Therefore, it is energetically favorable for metallic atoms with few valence electrons to give out electrons in order to achieve a full outer shell.
