State the octet rule. Define ionic bond. Show electron transfer in between atoms to form ionic bonds.

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In section 9.2, us saw how ions are created by losing electrons to do cations or by getting electrons to form anions. The astute leader may have actually noticed something: plenty of of the ion that type have eight electrons in your valence shell. Either atoms gain enough electrons to have actually eight electrons in the valence shell and also become the as necessary charged anion, or they lose the electron in their original valence shell; the lower shell, now the valence shell, has actually eight electron in it, therefore the atom becomes positively charged. For every little thing reason, having eight electron in a valence shell is a an especially energetically stable arrangement of electrons. The trend that atoms favor to have actually eight electron in your valence covering is dubbed the octet rule. As soon as atoms kind compounds, the octet ascendancy is not always satisfied for all atoms at all times, however it is a very great rule of ignorance for knowledge the type of bonding arrangements that atoms have the right to make.

It is not impossible to hurt the octet rule. Think about sodium: in its element form, it has actually one valence electron and is stable. The is rather reactive, however, and also does not call for a lot of energy to eliminate that electron to make the Na+ ion. We could remove another electron by adding even much more energy come the ion, to do the Na2+ ion. However, that calls for much much more energy 보다 is normally obtainable in historicsweetsballroom.comical reactions, so salt stops in ~ a 1+ charge after losing a single electron. It transforms out the the Na+ ion has a complete octet in its new valence shell, the n = 2 shell, i beg your pardon satisfies the octet rule. The octet dominion is a an outcome of trends in energies and is valuable in explaining why atoms kind the ion that they do.

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

\<\mathbfNa\, \cdot \; \; \; \; \; \; \; \; \; \; \mathbf\cdot \mathbf\ddot\underset.\: .Cl\mathbf\: :\>

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

For the Na atom to acquire an octet, the must lose an electron; for the Cl atom to gain an octet, that must get an electron. One electron move from the Na atom come the Cl atom:

\<\mathbfNa\, \cdot \curvearrowright \mathbf\cdot \mathbf\ddot\underset.\: .Cl\mathbf\: :\>

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

\<\mathbfNa^+\; \; \; \; \; \; \; \; \mathbf:\mathbf\ddot\underset.\: .Cl\mathbf\: :^-\>

\<\left < Ne \right >\; \; \; \; \; \left < Ne \right >3s^23p^6\>

Both species now have complete octets, and the electron shells room energetically stable. From basic physics, we recognize that opposite dues attract. This is what happens to the Na+ and Cl− ions:

\<\mathbfNa^+\; + \; \mathbf:\mathbf\ddot\underset.\: .Cl\mathbf\: :^-\rightarrow Na^+Cl^-\; \; or\; \; NaCl\>

where we have actually written the final formula (the formula for sodium chloride) as per the convention because that ionic compounds, there is no listing the fees explicitly. The attraction in between oppositely charged ion is called an ionic bond, and it is just one of the main species of historicsweetsballroom.comical binding in historicsweetsballroom.comistry. Ionic bonds are resulted in by electron transferring indigenous one atom come another.

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

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

\<\mathbfMg\,^2+\; + \; \mathbf:\mathbf\ddot\underset.\: .O\mathbf\: :^2-\; \; \; \; \; Mg^2+O^2-\; or\; MgO\>

Remember, in the final formula because that the ionic compound, we do not create the charges on the ions.

What around when one Na atom interacts through an O atom? The O atom demands two electron to finish its valence octet, but the Na atom supplies only one electron:

\<\mathbfNa\, \cdot \curvearrowright \mathbf\cdot \mathbf\ddot\underset.O\mathbf\: :\>

The O atom still does not have an octet that electrons. What we need is a 2nd Na atom come donate a 2nd electron come the O atom:

The oppositely charged ions tempt each various other to make CaCl2.

The strength of ionic bonding counts on two significant characteristics: the magnitude of the charges and also the dimension of the ion. The greater the size of the charge, the stronger the ionic bond. The smaller sized the ion, the more powerful the ionic bond (because a smaller sized ion size enables the ions to acquire closer together). The measured strength of ionic bonding is called the lattice energy. Part lattice energies are given in Table $$\PageIndex1$$ - Lattice Energies of part Ionic Compounds.

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

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