What happens during the formation of an ionic bond in calcium chloride?
Calcium gives valence electrons to both chlorine atoms so that they have a full outer shell. See below for details.
Let's first look at the formula for calcium chloride.
Now, let's find out its valence electrons.
The number of valence electrons in calcium is 2.
The number of valence electrons in chlorine is 7.
Now remember the Octet Rule : all electrons want to be like noble gases. (That is, with a full outer shell).
The fastest way for chlorine to have a full outer is to get 1 more valence electron.
The fastest way for calcium to have a
full outer shell is to get rid of both of its valence electrons.
But remember, there are
The calcium can supply them with one electron each! Look at how that happens in this diagram.
Since chlorine gained an electron, it is now negatively charged and is called an anion.
On the other hand, calcium gave away two electrons so it is now positively charged. This is called a cation.
Notice how both these ions have full outer shells.