ASP - Valence Electrons and Ionic Compound (Lesson)

Valence Electrons and Ionic Compounds

Forming Ions

Recall that groups of elements have the same number of valence electrons. Also recall which group of elements is the most stable. There is actually a relationship between these. There is an inherent stability in having an electron configuration that is like those of the noble gases, s²p⁶ or 8 valence electrons. This is known as the Octet Rule. (H, Li, Be, & B are exceptions to this rule as they will form ions that have the same electron configuration as He. He only has two valence electrons.)  

So, when atoms lose or gain electrons, they do so in an attempt to have the same electron configuration ending as the noble gases, or 8 valence electrons. When an atom loses or gains electrons, it becomes an ion. Let's look at sodium, for example. Click on the plus sign to reveal the answer. 

So, when sodium forms an ion, the attempt is to have 8 valence ( outermost s & p ) electrons and the configuration of a noble gas. Let's look at the ways sodium can achieve this.  

Now you try. How does Cl become an ion?  Answer the following questions. Click on the plus sign to reveal the answer. 

If you follow this method for each element, you will see a trend emerge. Below is what each group of representative elements does to become a stable ion.

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