State the octet rule. Specify ionic bond. Demonstrate electron transfer in between atoms to form ionic bonds.

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In ar 9.2, we saw how ions are created by shedding electrons to make cations or by gaining electrons to type anions. The astute reader may have actually noticed something: numerous of the ions that type have eight electrons in your valence shell. Either atoms gain enough electrons to have eight electrons in the valence shell and become the as necessary charged anion, or they lose the electron in their original valence shell; the lower shell, currently the valence shell, has eight electrons in it, for this reason the atom i do not care positively charged. For whatever reason, having eight electrons in a valence covering is a particularly energetically stable setup of electrons. The trend that atoms prefer to have eight electrons in their valence covering is dubbed the octet rule. When atoms form compounds, the octet dominance is not always satisfied for every atoms at all times, however it is a very an excellent rule of thumb for knowledge the kinds of bonding arrangements that atoms deserve to make.

It is not difficult to hurt the octet rule. Think about sodium: in its element form, it has one valence electron and is stable. It is fairly reactive, however, and also does not call for a lot of of power to eliminate that electron to do the Na+ ion. Us could remove one more electron by adding even an ext energy to the ion, to make the Na2+ ion. However, that requires much an ext energy than is normally obtainable in altoalsimce.orgistry reactions, so salt stops in ~ a 1+ charge after shedding a single electron. It turns out the the Na+ ion has a complete octet in its brand-new valence shell, the n = 2 shell, i beg your pardon satisfies the octet rule. The octet ascendancy is a an outcome of patterns in energies and also is advantageous in explaining why atoms kind the ion that lock do.

Now consider an Na atom in the existence of a Cl atom. The two atoms have actually these Lewis electron period diagrams and also electron configurations:

3s^1; ; ; ; left < Ne ight >3s^23p^5>

For the Na atom to acquire an octet, that must shed an electron; because that the Cl atom to obtain an octet, it must acquire an electron. One electron move from the Na atom come the Cl atom:

resulting in 2 ions—the Na+ ion and the Cl− ion:

; ; ; ; ; left < Ne ight >3s^23p^6>

Both types now have complete octets, and the electron shells space energetically stable. From an easy physics, we recognize that opposite charges attract. This is what happens to the Na+ and also Cl− ions:

where we have actually written the final formula (the formula for sodium chloride) together per the convention for ionic compounds, without listing the dues explicitly. The attraction in between oppositely charged ion is called an ionic bond, and it is just one of the main types of altoalsimce.orgistry bonds in altoalsimce.orgistry. Ionic bonds are resulted in by electron transferring native one atom to another.

In electron transfer, the variety of electrons shed must same the number of electrons gained. We witnessed this in the development of NaCl. A similar procedure occurs between Mg atoms and also O atoms, except in this case two electrons room transferred:


The two ions each have octets together their valence shell, and the 2 oppositely fee particles attract, making an ionic bond:

Remember, in the final formula for the ionic compound, we carry out not compose the fees on the ions.

What around when one Na atom interacts v an O atom? The O atom needs two electrons to finish its valence octet, however the Na atom supplies just one electron:

The O atom quiet does not have an octet of electrons. What we require is a second Na atom to donate a second electron to the O atom:


The oppositely fee ions attract each various other to do CaCl2.


The toughness of ionic bonding depends on two significant characteristics: the size of the charges and the size of the ion. The better the magnitude of the charge, the more powerful the ionic bond. The smaller sized the ion, the stronger the ionic bond (because a smaller ion size allows the ions to acquire closer together). The measured strength of ionic bonding is called the lattice energy. Part lattice energies are provided in Table (PageIndex1) - Lattice Energies of some Ionic Compounds.

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Table (PageIndex1): Lattice Energies of some Ionic CompoundsCompoundLattice power (kJ/mol)
LiF 1,036
LiCl 853
NaCl 786
NaBr 747
MgF2 2,957
Na2O 2,481
MgO 3,791

altoalsimce.orgistry Is Everywhere: Salt

The element sodium (part in the accompanying figure) is a an extremely reactive metal; given the opportunity, it will certainly react v the sweat on your hands and kind sodium hydroxide, i m sorry is a really corrosive substance. The element chlorine (part in the accompanying figure) is a pale yellow, corrosive gas that need to not be inhaled because of its poisonous nature. Carry these 2 hazardous building material together, however, and also they react to make the ionic compound salt chloride (part in the accompanying figure), known simply together salt.