1. Fig 8.17 Periodic Table of the Elements
Alkali Earth Metal
Noble Gas
Halogen
Alkali Metal
Period
Group

2. Show only valence electrons!
Electron dot notation for the representative elements
Fig 8.18
Show only valence electrons!

3. CHEMICAL BONDS
CHAP 9

4. Homework for Chap 9 Read p 229 - 246 Applying the Concepts: 1 – 13,
16 – 35, 38 – 44,

5. Compounds and Chemical Change
Elements are composed of extremely small particles called atoms.
Compounds are composed of atoms of more than one element held together by chemical bonds.
3. Molecule – smallest particle of a compound that can
exist and still retain characteristic chemical properties
Compounds occur as solids, liquids, and gases

6. Fig. 9.2 Common gases exist as atoms or molecules

7. Fig. 9.3 Energy is released Example of a chemical reaction
Burning magnesium (Mg)
in air
to produce magnesium oxide
(“milk of magnesia”)
Energy is released

8. Fig. 9.4 (A) Photosynthesis stores solar energy
Reactants
Products
Fig. 9.4 (B) Combustion releases solar energy

9. Fig 8.20 Electron dot notation for representative elements 1 83 4 5 6 7
Valence electrons – outermost electrons in an atom
Octet rule – atoms attempt to acquire 8 valence electrons

10. Fig. 9.5

11. Fig 8.21
energy + Na → Na+ + e−
energy + Ca →
energy + Al →
Ca e−
Al e− 1 8 2 3 4 5 6 7

12. Three Types of Chemical Bonds
Ionic bonds
Electrons are transferred from one atom to another
Occur between a metal atom and a nonmetal atom
(2) Covalent bonds
Electrons are shared between two atoms
Occur between two nonmetal atoms
Metallic bonds
Metal atoms share many electrons in a “sea” that is free to move throughout the metal

13. This energy is called the heat of formation
Formation of an ionic bond Na
11 protons
11 electrons
Na+
11 protons
10 electrons
+ e−
Cl-
17 protons
18 electrons Cl
17 protons
17 electrons
Net reaction: Na + Cl → Na+Cl− + energy
This energy is called the heat of formation

14. Fig. 9.6 Model of the sodium chloride crystal
No molecules in an ionic compound!
Formula unit + −
Na+ ions
Cl− ions

15. Fig. 9.7 The cubic crystal structure of sodium chloride

16. Ionic compounds consist of a combination of
Ionic compounds consist of a combination of positive ions and negative ions
Ions are formed as nonmetal atoms gain and metal atoms lose electrons to achieve stable noble gas structure
The sum of the charges on the positive ions and negative ions in each formula unit must equal zero
How do we determine the formula for an ionic compound?

17. Formula of Ionic Compounds
2 x +3 = +6
3 x -2 = -6
Al2O3
Al and O
Al3+
O2-
1 x +2 = +2
2 x -1 = -2
Ca and Br
CaBr2
Ca2+
Br-