So you're here to learn about bonding. Well first you need to learn why atoms bond together. We use a concept called "Happy Atoms". We figure most atoms want to be happy.
The idea behind happy atoms is that atomic shells like to be full. That's it. If you are an atom, and you have a shell, you want your shell full. Some atoms have too many electrons, one or two extra. These atoms like to give up their electrons. Some atoms are really close to having a full shell. These atoms go around looking for other atoms who want to give up an electron.
Simple, right? Let's take a look at some examples...
If you've been keeping up with CHEM4KIDS, you know about the 2-8-8 rule. The first shell is filled with 2 electrons, the second is filled with 8 electrons, and the third is filled with 8 (for the first 18 elements).
Anyway, you can see that Sodium and Magnesium have a couple of extra electrons. They, like all atoms, want to be happy. They have two possibilities. (1)They can try to get eight electrons to fill up their third shell. Or (2) they give up a few electrons and have a filled second shell. The way chemistry works, it's easier to give up a few electrons.
What a coincidence! There are other atoms who are interested in getting a few extra electrons...
Well right up there are Oxygen and Fluorine. Each is looking for a couple of electrons to make a filled shell. They have one filled shell with two electrons but their second shell wants to have eight. Now there are a couple of ways they can get the electrons. They can share electrons, making a covalent bond, or they can just borrow them, making an ionic bond.
So we've go a Sodium atom which has an extra electron. We've also got a Fluorine atom which is looking for one. Sometimes this happens...
So they work together and both wind up happy. Sodium gives up its extra electron. The Sodium has a full second shell and the Fluorine has a full second shell as well. Two happy atoms! That's one way things are able to bond together, by giving up and sharing electrons.