1. Ionic Compounds (“Ionic bonds”)
Caused by large Electronegativity difference (Δ EN) between two atoms
Using greater than or equal to (Δ EN ≥ 1.7 )
Not a True Chemical Bond (Def: sharing valence electrons)
Then what is it?? Answer:
It is actually 2 “things”
Moving of electrons occurs when atoms become ions
Coulombic force holding cations and anions together
Therefore, BASE UNIT IS IONS

2. 6.3
What are Ions?
An ion is an atom or group of atoms that has a positive or negative charge.
A cation is an ion with a positive charge.
An anion is an ion with a negative charge.
Why do atom form ions?
Δ EN ≥ 1.7 between the two atoms
Obeying the Rule of Eight (also called Octet Rule)
Rule of Eight
After bonding (movement of valence electrons), all “atoms” want eight valence electrons in their highest energy level (“valence shell”) except H (2ve-), Be (4ve-), B (6ve-)) and elements in the 3rd energy level or greater than can exceed eight.

3. 6.3
Ions
Metals elements lose valence electrons to form cation ions. Cation radii (IR) are always smaller than atomic radii (AR) [i.e. IR < AR]
When a sodium atom loses an electron, it becomes a positively charged ion. When a chlorine atom gains an electron, it becomes a negatively charged ion. Interpreting Diagrams What happens to the protons and neutrons during these changes?

4. As the previous slide shows, Why does sodium atom lose only one valence electron to form sodium ion (called cation)? Answer:
It needs to follow Rule of Eight.
Sodium atom electron configuration: Na : 1s22s22p63s1
After it lose 1 electron to form the sodium ion (Na1+), electron configuration is Na1+ : 1s22s22p6
So, electron configuration of sodium ion has a “full valence energy level or shell”
All metals will do same procedure (lose ve- to form positive ions or cations)

5. 6.3
Ions
Non-metal elements gain valence electrons to form anion ions. Anion radii (IR) are always larger than atomic radii (AR) [i.e. IR > AR]
When a sodium atom loses an electron, it becomes a positively charged ion. When a chlorine atom gains an electron, it becomes a negatively charged ion. Interpreting Diagrams What happens to the protons and neutrons during these changes?

6. As the previous slide shows, Why does chloride atom gain only one valence electron to form chlorine ion called chloride ion (called anion)? Answer:
It needs to follow Rule of Eight.
Chlorine atom electron configuration: Cl 1s22s22p63s13p5
After it gain 1 electron to form the chloride ion (Cl1-), electron configuration is Cl1- : 1s22s22p63p6
So, electron configuration of chloride ion has a “full valence energy level or shell”
All non-metals will do same procedure (gain ve- to form negative ions or anions)

7. So what does the ionic compound, Sodium chloride ( Na1Cl1) look like?
Green ball – Chloride ion
Black ball – Sodium ion
Source
Source:

8. Summary
When 2 atom (with Δ EN ≥ 1.7) get near each other, one atom gains ve- to form the anion and other atom loses ve-to form the cation.
“Ionic bond does not really exist, what it is valence electrons moving to form ions and then ions “sticking” together via coulombic force.
How many ve- gained/lost by each atom is governed by the Rule of Eight.
Other Powerpoint Presentation will explain more.