Most atoms carry out not have actually eight electrons in their valence electron shell. Part atoms have only a few electrons in their external shell, while some atoms lack only one or two electrons to have actually an octet. In situations where one atom has actually three or fewer valence electrons, the atom may shed those valence electron quite quickly until what stays is a reduced shell that includes an octet. Atoms that lose electrons obtain a positive charge as a resultbecause they are left v fewer negatively fee electrons to balance the confident charges of the protons in the nucleus. Positive charged ion are called cations. Most metals come to be cations once they make ionic compounds.

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Cations

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

The cation developed in this way, Na+, is referred to as the sodium ion to distinguish it indigenous the element. The outermost covering of the salt ion is the second electron shell, which has actually eight electron in it. The octet dominion has been satisfied. Number (PageIndex1) is a graphical explicate of this process.

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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 actually 18 electrons and also has a 1− charge.

The names for hopeful and an unfavorable ions space pronounced CAT-eye-ons and also ANN-eye-ons, respectively.

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In numerous cases, elements that belong come the same team (vertical column) ~ above the regular table kind ions with the same charge because they have the same variety of valence electrons. Thus, the regular table becomes a device for mental the fees on plenty of ions. For example, all ions made native alkali metals, the an initial column top top the regular table, have actually a 1+ charge. Ions made indigenous alkaline earth metals, the 2nd group on the regular table, have a 2+ charge. Top top the other side that the periodic table, the next-to-last column, the halogens, kind ions having actually a 1− charge. Number (PageIndex3) shows exactly how the fee on plenty of ions can be suspect by the place of an facet on the routine table. Note the convention of an initial writing the number and also then the authorize on a ion v multiple charges. The barium cation is created Ba2+, not Ba+2.