1. Formation of Ionic Compounds

2. - a combination of different element - can be ionic or covalent
compound
- a combination of different element
- can be ionic or covalent
compounds
covalent
ionic

3. Valence shell
In an atom the outermost shell of electrons, the valence shell, determines its interaction with other atoms

4. Octet rule
all atoms strive to have the same valence shell as their closest noble gas

6. Lewis symbols
Since how atoms react is dictated by the number of electrons in their valence shell Lewis symbols can be used to draw valence shells, ex. Na

7. first place electrons, one at a time, at the 12, 3, 6, and 9 o’clock positions, add more electrons by pairing them, one at a time, in the same order as you placed the first four electrons

8. Formation of Ions
atoms are most stable when their valence shell is full, like that of Noble Gases
they achieve this by gaining or losing electrons, depending on how many they have
 if they have less than 4 e they will lose them
 if they have more than 4 e they will gain them

10. ions
atoms that lose or gain an electron are called ions
ions can also be represented by Lewis symbols: the Lewis symbol is enclosed in square brackets, the charge of the ion is placed outside the brackets.

12. cations
positively charged ions, have lost electrons, ex. Na,
metals lose electrons and become cations
sodium atom sodium ion

13. anions
negatively charged ions, have gained electrons, ex. Cl
nonmetals gain electrons and become anions
chlorine atom chloride ion

14. Ionic bonds form between metals and nonmetals.
since opposites attract, when a cation and anion come into contact, they experience an electrostatic force of attraction, resulting in a chemical bond known as an ionic bond

15. ionic compounds
ex. NaCl
-crystals (or crystal salts) of positive and negative ions held together by electrostatic forces (ionic bonds)
-they form formula units (not molecules)