1. 7-1 Lewis Dot Diagrams

2. Dot Diagrams . : : . : . . : . : . : : . : : . . : . : . : : . : : [x]
s2p6 H . He : s2
s2p1
s2p2
s2p3
s2p4
s2p5 C : . : . N X . X : . : . O Be : : . F : Ne : . X Al . : . X : . : X : . X X : X : +4 -4 +1 +2 +3 -3 -2 -1
[x]
[x]
[x]
[:x:] :
[:x:] :
[:x:] :
Ion formation:
Loss (oxidation) or gain (reduction) of electrons

3. [ ] [ ] A1. NaI I Na Does it start with a metal? Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots. -1 [ +1 ] [ ] Na I

4. Rules for Ionic Combos
If the combo starts with a metal, assume it is all charged and use brackets.
Put opposite charges next to each other and similar charges away.
Metal ions always are positive, non-metals are negative.
Determine the charges by columns in the periodic table.
Negative (-) ions will end up with 8 electron dots, positive (+) ions have 0.

5. [ ] [ ] A2. BaO O Ba Does it start with a metal? Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots. -2 [ +2 ] [ ] Ba O

6. [ ] [ ] [ ] A3. CaF2 F F Ca Does it start with a metal?
Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots. -1 -1 [ ] [ +2 ] [ ] F Ca F

7. [ ] [ ] [ ] [ ] A4. K3P K K P K Does it start with a metal?
Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots. [ +1 ] [ -3 ] [ +1 ] K P K [ ] +1 K

8. B1. H2 H H If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 2.
Place 2 dots between each adjacent atoms to bond them. H H

9. Rules for Covalent Combos
Make sure you have the right number of dots or you will never get the right answer.
Electron dots will always be in pairs.
Every non-metal but hydrogen must have 8 electron dots to be stable.
Hydrogen only needs 2 electron dots to be stable.
If you are short, move pairs in between to make double or triple bonds

10. B2. Cl2 Cl Cl If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each Cl has 7 electron for a total of 14.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom. Cl Cl
Each atom has a complete octet (8).

11. H S H B3. H2S If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 2. A S atom has 6. The total is 8 dots.
Place 2 dots between each adjacent atoms to bond them.
Hydrogens only need 2 dots, other non-metals need 8.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom. H S H
Each atom has an octet (8) or complete valence shell.

12. B4. OF2 F O F If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each F has 7 electrons for a total of 14. An O atom has 6. The total is 20 dots.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom. F O F
Each atom has a complete octet (8).

13. H N H H B5. NH3 If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 3. An N atom has 5.
The total is 8 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots. H N H H

14. Cl P Cl Cl B6. PCl3 If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each Cl has 7 electrons for a total of 21. A P atom has 5.
The total is 26 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom. Cl P Cl Cl

15. B7. CH4 H H C H H If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 4. An C atom has 4. The total is 8 dots.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots. H H C H H

16. I H C H H B8. CH3I If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 3. An C atom has 4.
An iodine has 7 dots. The total is 14 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom. I H C H H

17. C1. O2 O O Each O has 6 electron for a total of 12 dots.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom.
H only requires 2 dots. Other atoms require 8 dots.
If you are short, move pairs in between to make double or triple bonds O O
Now each atom has an octet (8) of valence electrons.

18. C2. CO2
Each O has 6 electron for a subtotal of 12. The C has 4 for a grand total of 16 dots.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom.
H only requires 2 dots. Other atoms require 8 dots.
If you are short, move pairs in between to make double or triple bonds O C O
Double bonds give each atom 8 electrons.

19. C3. C2H2 H C H C A triple bond in needed so each atom has 8 electrons.
Each C has 4 electron for a subtotal of 8. Each H has 1 for a grand total of 10 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom.
H only requires 2 dots. Other atoms require 8 dots.
If you are short, move pairs in between to make double or triple bonds H C C H
A triple bond in needed so each atom has 8 electrons.

20. D1. H3O+
Each H has 1 electron for a subtotal of 3. An O has 6.
A positive charge means 1 electron is missing. (Negative charge indicates extra electrons.)
The total is 8 dots.
O has to be central. H’s can only make 1 bond.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place in brackets & label the charge. [ ] H O H H +1

21. D2. NH4+
Each H has 1 electron for a subtotal of 4. An N has 5.
A positive charge means 1 electron is missing. (Negative charge indicates extra electrons.)
The total is 8 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place in brackets & label the charge. [ ] H +1 H N H H

22. [ ] H O D3. OH- The H has 1 electron. An O has 6.
A negative charge means there is 1 extra electron. (Positive charge indicates missing electrons.)
The total is 8 dots.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom.
Place in brackets & label the charge. -1 [ ] H O

23. D4. PO4-3
Each O has 6 electrons for 24. A P atom has 5.
A negative 3 charge means 3 extra electrons. (Negative charge indicates extra electrons.) The total is 32 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom.
Place in brackets & label the charge. [ ] O -3 O P O O

24. Review Examples E1 – AlCl3 E4 – OCl2 E8 – HCN
Get out your periodic table & dot diagram handout.

25. [ ] [ ] [ ] [ ] E1. AlCl3 Cl Al Cl Cl Does it start with a metal?
Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots. +3 -1 [ ] [ ] [ ] Cl Al Cl
Done! -1 [ ] Cl -1

26. E4. OCl2 Cl O Cl If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each Cl has 7 electrons for a total of 14.
An O atom has 6.
The total is 20 dots.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom. Cl O Cl
Each atom has a complete octet (8).

27. E8. HCN
H is a non-metal so this is covalent.
Add up the valence electron dots for each atom.
The C has 4 electrons.
The N has 5 dots.
The H has 1 for a grand total of 10 dots.
The 1st atom is usually central, but H can only make 1 bond.
The C is then central.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4 sides of each atom.
H only requires 2 dots. Other atoms require 8 dots.
If you are short, move pairs in between to make double or triple bonds H C N
A triple bond in needed so the C & N each have 8 electrons.

28. Dot Diagrams Quiz Formula Ionic or Covalent? (1st element?)
SBr2
SrF2
SiO2