Most atoms perform not have eight electrons in their valence electron shell. Some atoms have only a few electrons in their external shell, while some atoms lack only one or two electrons to have an octet. In instances where an atom has three or under valence electrons, the atom may lose those valence electron quite quickly until what stays is a reduced shell that has an octet. Atom that lose electrons obtain a optimistic charge as a resultbecause they are left with fewer negatively charged electrons come balance the confident charges of the proton in the nucleus. Positive charged ions are dubbed cations. Most metals come to be cations as soon as they do ionic compounds.

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Cations

A neutral salt atom is most likely to accomplish an octet in that outermost covering by losing its one valence electron.

The cation created in this way, Na+, is called the sodium ion to differentiate it from the element. The outermost shell of the sodium ion is the 2nd electron shell, which has actually eight electrons in it. The octet dominion has been satisfied. Figure (PageIndex1) is a graphical depiction of this process.

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

The names for optimistic and an unfavorable ions are pronounced CAT-eye-ons and ANN-eye-ons, respectively.

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In numerous cases, elements that belong to the same team (vertical column) on the regular table type ions with the same charge due to the fact that they have actually the same number of valence electrons. Thus, the regular table becomes a device for remembering the fees on many ions. For example, all ion made from alkali metals, the very first column ~ above the routine table, have actually a 1+ charge. Ion made indigenous alkaline earth metals, the second group top top the periodic table, have a 2+ charge. On the various other side that the periodic table, the next-to-last column, the halogens, type ions having a 1− charge. Number (PageIndex3) shows just how the fee on countless ions have the right to be predicted by the place of an element on the regular table. Note the convention of an initial writing the number and also then the sign on a ion through multiple charges. The barium cation is written Ba2+, not Ba+2.