Most atoms execute not have actually eight electron in your valence electron shell. Part atoms have actually only a couple of electrons in their outer shell, while part atoms lack only one or two electrons to have actually an octet. In situations where an atom has three or under valence electrons, the atom may shed those valence electrons quite quickly until what continues to be is a reduced shell that contains an octet. Atom that shed electrons obtain a optimistic charge together a an outcome because they space left through fewer negatively charged electrons come balance the optimistic charges the the protons in the nucleus. Positively charged ions are called cations. Many metals come to be cations when they make ionic compounds.

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Some atom have almost eight electron in your valence shell and can gain additional valence electrons until they have actually an octet. As soon as these atoms obtain electrons, they acquire a negative charge since they now possess an ext electrons 보다 protons. Negative charged ion are referred to as anions. Most nonmetals become anions when they make ionic compounds.

Electron Transfer

We can use electron configurations to show the electron transfer process between sodium atoms and chlorine atoms.

Na: 1s22s22p63s1

As demonstrated in instance 1, salt is most likely to achieve an octet in the outermost covering by losing its one valence electron. The remaining varieties has the following electron configuration:


The cation produced in this way, Na+, is referred to as the salt ion to distinguish it from the element. The outermost shell of the salt ion is the second electron shell, which has eight electron in it. The octet ascendancy has to be satisfied. Figure \(\PageIndex1\) is a graphical relenten of this process.


Figure \(\PageIndex1\): The development of a sodium Ion. Top top the left, a sodium atom has 11 electrons. On the right, the sodium ion only has 10 electrons and a 1+ charge.

A chlorine atom has actually the following electron configuration:

Cl: 1s22s22p63s23p5

Only one an ext electron is necessary to attain an octet in chlorine’s valence shell. (In table salt, this electron originates from the sodium atom.) The electron configuration of the brand-new species that outcomes is together follows:


In this case, the ion has the exact same outermost shell as the original atom, but now the shell has actually eight electrons in it. When again, the octet preeminence has been satisfied. The result anion, Cl−, is called the chloride ion; keep in mind the slight adjust in the suffix (-ide rather of -ine) to create the surname of this anion. Number \(\PageIndex2\) is a graphical depiction of this process.


With 2 oppositely fee ions, over there is one electrostatic attraction between them since opposite dues attract. The resulting mix is the compound salt chloride. An alert that there space no leftover electrons. The variety of electrons shed by the salt atom (one) amounts to the variety of electrons acquired by the chlorine atom (one), therefore the compound is electrically neutral. In macroscopic samples of sodium chloride, there are billions and billions the sodium and also chloride ions, although there is always the same variety of cations and also anions.

In many cases, aspects that belong come the same group (vertical column) ~ above the regular table kind ions through the very same charge due to the fact that they have the same variety of valence electrons. Thus, the periodic table becomes a tool for mental the dues on plenty of ions. Because that example, all ions made native alkali metals, the an initial column ~ above the routine table, have actually a 1+ charge. Ions made indigenous alkaline earth metals, the 2nd group on the routine table, have actually a 2+ charge. On the various other side that the routine table, the next-to-last column, the halogens, type ions having a 1− charge. Figure \(\PageIndex3\) shows exactly how the fee on plenty of ions can be predicted by the place of an element on the periodic table. Note the convention of very first writing the number and also then the sign on a multiply charged ion. The barium cation is created Ba2+, no Ba+2.

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and the depiction for chlorine is as follows:


The transport of electrons deserve to be shown easily with Lewis diagrams:

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Example \(\PageIndex1\)

Starting v lithium and bromine atoms, use Lewis diagrams to display the development of the ionic link LiBr.


From the regular table, we watch that lithium is in the same column as sodium, so the will have actually the same valence shell electron configuration. That way that the neutral lithium atom will have actually the exact same Lewis diagram the the sodium atom has. Similarly, bromine is in the same shaft as chlorine, so the will have the same Lewis diagram the chlorine has. Therefore,