Electrons exchange energy in an attempt to obtain stability. All known chemical elements are shown on the periodic table. They range from the most reactive element group, which is the first group on the left of the table, the alkali metals, to the least reactive which is Group 8 the noble gasses. The most active group of metals on the periodic table, the alkali metals, have only one valence electron.
Alkali metals are so reactive that they are not found naturally by themselves. You will find alkali metals in nature as parts of compounds. The most reactive non-metal element is fluoride, one of the Halogens, the non-metals group that is most reactive.