1. Ions and Ionic Bonding

2. A Review
Atoms consist of protons, neutrons and electrons. The protons and neutrons are located in the nucleus of the atom. The electrons exist in energy levels or shells around the nucleus
The outermost shell of an atom is called the valence shell. The number of electrons in the valence shell tells us how the atom will interact with other atoms

3. The Octet Rule
Atoms are most stable or “happy” when their valence shells has eight electrons.
The only elements that have eight electrons in their valence shell are the noble gases (group 8/18).
So how do other elements get 8 electrons in their valence shells?

4. Let’s Make a Deal!!! Why are sodium and chlorine unhappy?
What kind of deals can you think of that would make them both happy?

5. Let’s Make a Deal!! Why did sodium get smaller?
Why did chlorine get larger?
Where did the positive and negative charges come from?
The students already have the notion that when you lose something, you become negative and vice versa. This may cause them to reverse the charges.

6. Opposites Attract!!

7. What Just Happened?!?!
Sodium had 1 electron in its valence shell and chlorine had seven electrons in its valence shell
They both needed the octet to be stable
It was easier for sodium to give up its electron than try to gain seven
It was easier for chlorine to gain one more electron than try to lose seven

8. What Just Happened?!?!
Sodium gave up its one electron to chlorine. The shell below the valence shell is full (it has an octet already). So sodium is more stable.
Chlorine has an octet, thanks to sodium’s electron, so it is stable.
Since sodium lost an electron, its electron cloud gets smaller.
Since chlorine gains an electron, its electron cloud gets larger.

9. Forming the bond
Sodium loses one electron, so it has one less electron than proton. Protons have a positive charge so the sodium will have an overall positive charge. The sodium atom will now be a cation.
Chlorine gains one electron, so it has one more electron than proton. Electrons have a negative charge so the chlorine will have an overall negative charge. The chlorine atom will now be an anion.

10. Some Animations Interaction between Sodium and Chlorine atoms
The Chemical reaction for forming Sodium Chloride

11. What elements like to gain electrons?
What elements like to lose electrons?

12. A Look at the Periodic Table

13. The Answer!!
Metals have fewer than 4 electrons in their outer shells. They would rather lose electrons to form cations.
Nonmetals have more than 4 electrons in their outer shells. They would rather gain electrons to form anions.

14. More Examples
K and F
Ca and S
Al and N