Most atoms carry out not have actually eight electrons in their valence electron shell. Some atoms have just a few electrons in their external shell, while some atoms absence only one or 2 electrons to have actually an octet. In cases where an atom has actually 3 or fewer valence electrons, the atom may lose those valence electrons rather easily until what continues to be is a reduced shell that consists of an octet. Atoms that shed electrons gain a positive charge as a resultbereason they are left with fewer negatively charged electrons to balance the positive charges of the protons in the nucleus. Positively charged ions are called cations. Most metals end up being cations when they make ionic compounds.

You are watching: Why do atoms gain or lose electrons


Cations

A neutral sodium atom is most likely to achieve an octet in its outerthe majority of shell by losing its one valence electron.

The cation created in this way, Na+, is referred to as the sodium ion to identify it from the aspect. The outera lot of shell of the sodium ion is the second electron shell, which has actually eight electrons in it. The octet preeminence has actually been satisfied. Figure (PageIndex1) is a graphical depiction of this process.

*
api/deki/files/114134/3.2B.jpg?revision=1" />Figure (PageIndex2): The Formation of a Chlorine Ion. On the left, the chlorine atom has actually 17 electrons. On the best, the chloride ion has actually 18 electrons and also has a 1− charge.

The names for positive and negative ions are pronounced CAT-eye-ons and also ANN-eye-ons, respectively.

See more: What Does All Hail The King Mean Ing Of "Hail To The King", All Hail King Jesus

In many cases, facets that belengthy to the same team (vertical column) on the periodic table create ions via the exact same charge bereason they have the exact same variety of valence electrons. Hence, the periodic table becomes a tool for remembering the charges on many ions. For example, all ions made from alkali metals, the initially column on the regular table, have actually a 1+ charge. Ions made from alkaline earth steels, the second team on the regular table, have a 2+ charge. On the other side of the routine table, the next-to-last column, the halogens, develop ions having actually a 1− charge. Figure (PageIndex3) mirrors how the charge on many kind of ions deserve to be predicted by the place of an aspect on the routine table. Note the convention of first creating the number and then the authorize on a ion through multiple charges. The barium cation is created Ba2+, not Ba+2.