1. Electron Configuration and Lewis Dot Diagrams
We have seen that LDD’s represent the valence electrons only. Here we see Fluorine is represented by the symbol F surrounded by the 7 valence electrons. (10 sec)
Both of these mean the same thing

2. F Lewis Dot Diagram Element symbol represents: Dots represent: Nucleus
AND
All inner core electrons
Dots represent:
Valence electrons (outer shell – Highest occupied energy level) F
So make sure your notes have these key points
(15 sec)

3. Stable Electron Configurations – Lewis Dot Diagrams
Assigning valence electrons across the period table is simple group

4. Stable Electron Configurations – Lewis Dot Diagrams

5. Stable Electron Configurations – Lewis Dot Diagrams

6. Stable Electron Configurations – Lewis Dot Diagrams

7. Stable Electron Configurations – Lewis Dot Diagrams

8. Stable Electron Configurations – Lewis Dot Diagrams

9. Stable Electron Configurations – Lewis Dot Diagrams

10. Stable Electron Configurations – Lewis Dot Diagrams

11. Stable Electron Configurations – Lewis Dot Diagrams

12. Formation of Ions
When an atom gains or loses an electron(s)  atom is no longer neutral.
# of Protons NO LONGER EQUAL # of electrons
Definition:
ION = atom (or group of atoms) with positive (+) or negative (-) net electric charge.

13. Formation of Ions ANION = Ion with a negative (-) charge
[Memory aid: anion = A Negative ION]
Example: Chlorine
atomic # 17
Halogen Family/Group 7A
7 Valence Electrons
Neutral (but not stable) - 17 protons and 17 electrons
To become stable – gain 1 electron in outer e- shell
Now have 1 more e- than proton = -1 net charge
Symbol is written Cl- or Cl1-

14. Formation of Ions CATION = Ion with a positive charge Example: Sodium
atomic # 11
Alkali Metal Family/Group 1A
1 Valence Electron
Neutral (but not stable) -11 protons and 11 electrons
To become stable – lose the 1 electron in outer e- shell
Now has 1 more proton than electron = 1+ net charge
Symbol is written Na+ or Na1+

15. Bonding
MNM
MM
NMNM
Elements achieve stable electron configurations by transferring or sharing electrons between atoms
Transferring Electrons -
Those with <4 valence electrons “LEND” them
These elements “lose” valence electrons OR
Those with >4 valence electrons “BORROW” them
These elements “gain” electrons

16. Formation of Ions & Bonding
Sodium reacts with chlorine 
electron transferred from sodium to chlorine
Each atom ends up more stable

17. Formation of Ions & Bonding
Sodium reacts with chlorine 
electron transferred from sodium to chlorine
Each atom ends up more stable

18. Formation of Ions & Bonding

19. LDD’s for Ions - + Na Cl

20. Ionic Bonding Chemical bond Opposites attract Ionic bond
Chemical bond = force that holds atoms or ions together as a unit.
Opposites attract
Particle(s) with negative charge attracts particle(s) with positive charge.
Ionic bond
Force that holds cations and anions together and which involves the transfer of electrons.
Bond occurs between a metal and a nonmetal

21. Mg2+ , Cl- Ionic Bonding Ions Lewis Dot Ionic Compounds
What is the chemical formula for magnesium chloride?
Mg and Cl
First determine the Lewis Dot Diagram and Ions for each element:

22. Ionic Bonding
Mg + 2Cl OR
Mg atom cannot reach a stable electron configuration by giving up just 1 valence electron or reacting with just 1 chlorine atom.

23. Ionic Bonding Mg transfers 2 electrons, one to each of the 2 Cl atoms.
After transfer 
Charge on the magnesium ion is 2+
Charge on the 2 chloride ions is 1-

24. - - Ionic Bonding 2+ Formula for magnesium chloride is MgCl2
When it’s ionic the electrons are completely donated so they should not be drawn as shared electrons

25. Covalent Bonding Non –metal with Non-metal Eg CH4
Covalent compounds have real bonds shared electrons so the LDD should have shared electrons and they may not be shared equally but must be represented as shared