Most atoms perform not have eight electrons in their valence electron shell. Part atoms have actually only a few electrons in their external shell, while some atoms lack only one or two electrons to have an octet. In cases where an atom has three or under valence electrons, the atom may shed those valence electron quite quickly until what stays is a reduced shell that consists of an octet. Atom that shed electrons acquire a positive charge together a resultbecause they space left with fewer negatively charged electrons to balance the confident charges that the protons in the nucleus. Positively charged ion are called cations. Most metals become cations when they do ionic compounds.

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A neutral sodium atom is likely to attain an octet in that outermost shell by shedding its one valence electron.

\<\ceNa \rightarrow Na^+ + e^-\>

The cation produced in this way, Na+, is dubbed the salt ion to distinguish it native the element. The outermost covering of the salt ion is the second electron shell, which has actually eight electrons in it. The octet dominance has been satisfied. Figure \(\PageIndex1\) is a graphical depiction of this process.

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

The name for confident and an adverse ions room pronounced CAT-eye-ons and also ANN-eye-ons, respectively.

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In countless cases, aspects that belong come the same group (vertical column) top top the regular table type ions through the very same charge because they have actually the same number of valence electrons. Thus, the regular table becomes a tool for psychic the dues on many ions. For example, all ions made indigenous alkali metals, the an initial column top top the periodic table, have actually a 1+ charge. Ion made native alkaline planet metals, the second group ~ above the regular table, have actually a 2+ charge. On the various other side the the periodic table, the next-to-last column, the halogens, kind ions having actually a 1− charge. Figure \(\PageIndex3\) shows exactly how the charge on numerous ions have the right to be suspect by the location of an aspect on the periodic table. Note the convention of very first writing the number and also then the sign on a ion v multiple charges. The barium cation is composed Ba2+, not Ba+2.