1. Gilbert Newton Lewis (surrounded by pairs of electrons)
Ionic bonding,
Lewis Dot Diagrams
Gilbert Newton Lewis (surrounded by pairs of electrons)

2. Please work ahead if you finish a section before the rest of the class.

3. Lewis diagrams (Q1, Q2)
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Lewis suggested a means of keeping track of outer (or valence) electrons
Read handout up to “The Octet Rule”. Do Question 1 and Question 2 Q1 Ne Sb Rb F Q2 P P P P

4. Ions and the octet rule (Q3)
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Read the remainder of the handout. Do Q3. Br P Ne Al Ca
Noble gas Kr
Ar (3)
Ne (0)
Ne (3)
Ar (2)
(spaces)
(1) –
Ion Br
P 3–
none
Al 3+
Ca 2+

5. Overview: Types of Bonds (Q4)
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There are 2 bond types : ionic and covalent
In ionic bonding one atom has a stronger attraction for electrons than the other, and “steals” an electron from a second atom
In covalent bonding the attraction for electrons is similar for two atoms. They share their electrons to obtain an octet.
Read “types of bonds” on handout. Do Q4.
MgO
(ionic),
CaCl2
(ionic),
SO2
(covalent),
PbCl2
(ionic),
CCl4
(covalent),
CH4
(covalent)

6. Ionic bonding Ionic bonding involves 3 steps (3 energies)
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Ionic bonding involves 3 steps (3 energies)
1) loss of an electron(s) by one element, 2) gain of electron(s) by a second element, 3) attraction between positive and negative e– 1) 2) Na Cl 3)
Cl–
Na+
Cl–
Na+

7. Ionic bonding (Q5 - Li + Cl)
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Ionic bonding (stealing/transfer of electrons) can be represented in three different ways
Read the remainder of handout. Do Q5.
Li + Cl  [Li]+[Cl]–
3p+
4n0
2e-
17p+
18n0
8e-8e-2e
3p+
4n0
2e-1e-
17p+
18n0
7e- 8e- 2e-
1e- Li Cl
[ Cl ]–
[Li]+

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Ionic bonding: Mg + O
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Mg + O  [Mg]2+[O]2–
12p+
12n0
2e- 8e- 2e-
6e- 2e-
8n0
8p+
8e- 2e-
8n0
8p+
1e-
12p+
12n0
2e- 8e-
1e- O Mg
[ O ]2–
[Mg]2+
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