1. Ionic Bonds and Ionic Compounds
7.2
In many coastal countries that have warm, relatively dry climates, salt is produced by the evaporation of seawater. You will learn how cations and anions combine to form stable compounds such as sodium chloride.

2. Formation of Ionic Compounds
7.2
Formation of Ionic Compounds
Compounds composed of cations and anions are called ionic compounds.
Although they are composed of ions, ionic compounds are electrically neutral.
The charges of the ions balance each other and the compound has no charge

3. Formation of Ionic Compounds
7.2
Formation of Ionic Compounds
Aluminum metal and the nonmetal bromine react to form an ionic solid, aluminum bromide.
Aluminum metal and the nonmetal bromine react to form an ionic solid, aluminum bromide.

4. Formation of Ionic Compounds
7.2
Formation of Ionic Compounds
Ionic Bonds
The electrostatic forces that hold ions together in ionic compounds are called ionic bonds.

5. Formation of Ionic Compounds
7.2
Formation of Ionic Compounds
Formula Units
A chemical formula shows the kinds and numbers of atoms in the smallest representative unit of a substance.
A formula unit is the lowest whole-number ratio of ions in an ionic compound.

6. Formation of Ionic Compounds
7.2
Formation of Ionic Compounds
NaCl is the chemical formula for sodium chloride.
Sodium cations and chloride anions form a repeating three-dimensional array in sodium chloride (NaCl). Inferring How does the arrangement of ions in a sodium chloride crystal help explain why the compound is so stable?

7. Conceptual Problem 7.2

8. Conceptual Problem 7.2

9. Conceptual Problem 7.2

10. Conceptual Problem 7.2

11. Properties of Ionic Compounds
7.2
Properties of Ionic Compounds
Properties of Ionic Compounds
What are three properties of ionic compounds?
Most ionic compounds are crystalline solids at room temperature.
Ionic compounds generally have high melting points
Ionic compounds are brittle

12. Properties of Ionic Compounds
7.2
Properties of Ionic Compounds
The orderly arrangement of component ions produces the beauty of crystalline solids.
The beauty of crystalline solids, such as these, comes from the orderly arrangement of their component ions.

13. Properties of Ionic Compounds
7.2
Properties of Ionic Compounds
The coordination number of an ion is the number of ions of opposite charge that surround the ion in a crystal.
In NaCl, each ion has a coordination number of 6.
Sodium chloride and cesium chloride form cubic crystals. a) In NaCl, each ion has a coordination number of 6. b) In CsCl, each ion has a coordination number of 8. c) Titanium dioxide forms tetragonal crystals. In TiO2, each Ti4+ ion has a coordination number of 6, while each O2- ion has a coordination number of 3.

14. Properties of Ionic Compounds
7.2
Properties of Ionic Compounds
In CsCl, each ion has a coordination number of 8.
In TiO2, each Ti4+ ion has a coordination number of 6, while each O2- ion has a coordination number of 3.
Sodium chloride and cesium chloride form cubic crystals. a) In NaCl, each ion has a coordination number of 6. b) In CsCl, each ion has a coordination number of 8. c) Titanium dioxide forms tetragonal crystals. In TiO2, each Ti4+ ion has a coordination number of 6, while each O2- ion has a coordination number of 3.

15. Properties of Ionic Compounds
7.2
Properties of Ionic Compounds
Ionic compounds can conduct an electric current when melted or dissolved in water.
When sodium chloride melts, the sodium and chloride ions are free to move throughout the molten salt. If a voltage is applied, positive sodium ions move to the negative electrode (the cathode), and negative chloride ions move to the positive electrode (the anode). Predicting What would happen if the voltage was applied across a solution of NaCl dissolved in water?

16. 7.3
Bonding in Metals
You have probably seen decorative fences, railings, or weathervanes made of a metal called wrought iron. In this section, you will learn how metallic properties derive from the way that metal ions form bonds with one another.

17. Metallic Bonds and Metallic Properties
7.3
Metallic Bonds and Metallic Properties
The valence electrons of metal atoms can be modeled as a sea of electrons.
The valence electrons are mobile and can drift freely from one part of the metal to another.
Metallic bonds consist of the attraction of the free-floating valence electrons for the positively charged metal ions.

18. Metallic Bonds and Metallic Properties
7.3
Metallic Bonds and Metallic Properties
Metals are ductile—that is, they can be drawn into wires.
A metal rod can be forced through a narrow opening in a die to produce wire. a) As this occurs, the metal changes shape but remains in one piece. b) If an ionic crystal were forced through the die, it would shatter. Interpreting Diagrams What causes the ionic crystal to break apart?

19. Metallic Bonds and Metallic Properties
7.3
Metallic Bonds and Metallic Properties
A force can change the shape of a metal. A force can shatter an ionic crystal.
A metal rod can be forced through a narrow opening in a die to produce wire. a) As this occurs, the metal changes shape but remains in one piece. b) If an ionic crystal were forced through the die, it would shatter. Interpreting Diagrams What causes the ionic crystal to break apart?

20. Crystalline Structure of Metals
7.3
Crystalline Structure of Metals
Crystalline Structure of Metals
These tomatoes have a
closed-packed arrangement.
Similar arrangements can
be found in the crystalline
structure of metals.
These tomatoes illustrate a pattern called a hexagonal close-packed arrangement.

21. Crystalline Structure of Metals
7.3
Crystalline Structure of Metals
Metal atoms are arranged in very compact and orderly patterns.
Metal atoms crystallize in characteristic patterns. a) Chromium atoms have a body-centered cubic arrangement. b) Gold atoms have a face-centered cubic arrangement. c) Zinc atoms have a hexagonal close-packed arrangement. Inferring Which of these arrangements is the most closely packed?

22. 7.3
Alloys
Alloys are mixtures composed of two or more elements, at least one of which is a metal.
Alloys are important because their properties are often superior to those of their component elements.

23. 7.3
Alloys
Bicycle frames are often made of titanium alloys that contain aluminum and vanadium.
Bicycle frames are often made of titanium alloys that contain aluminum and vanadium.

24. 7.3
Alloys
The most important alloys today are steels. Steels have a wide range of useful properties, such as corrosion resistance, ductility, hardness, and toughness.

25. 7.2 Section Quiz.
7.2 and 7.3.

26. 7.2 Section Quiz.
1. Which chemical formula is incorrect?
KF2
CaS
MgO
NaBr

27. 7.2 Section Quiz.
2. Ionic compounds can conduct an electric current
only when melted.
when melted or dissolved in water.
only when dissolved in water.
when solid or melted.

28. 7.2 Section Quiz.
3. At room temperature, most ionic compounds are
crystalline solids.
liquids.
gases.
soft, low melting-point solids.

29. 7.3 Section Quiz.
1. The valence electrons of metals can be modeled as
a body-centered cube.
octets of electrons.
a rigid array of electrons.
a sea of electrons.

30. 7.3 Section Quiz.
2. In most metals, the atoms are
free to move from one part of the metal to another.
arranged in a compact and orderly pattern.
placed at irregular locations.
randomly distributed.

31. 7.3 Section Quiz.
3. Alloys are important because they
are pure substances.
are the ores from which metals can be refined.
can have properties superior to those of their components.
are produced by the combustion of metals.