4. Compounds composed of
cations and anions are called
ionic compounds.
Ionic compounds are
electrically neutral.
(positive charges always
equal the negative charges)
13. •A chemical formula shows the
kinds and numbers of atoms
in the smallest representative
unit of a substance.
14. •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.
15. NaCl is the chemical formula
for sodium chloride.
16. NaCl is the chemical formula
for sodium chloride.
17. NaCl is the chemical formula
for sodium chloride.
18. NaCl is the chemical formula
for sodium chloride.
19. Determining formulas for ionic
compounds
The positive charges must equal
the negative charges, because
the compound is neutral.
Mg2+ and Cl- make MgCl2
because you need 2 Cl- to cancel
21. What is the formula of a compound
containing ions of Al and O?
22. What is the formula of a compound
containing ions of Al and O?
Al3+ O2-
23. What is the formula of a compound
containing ions of Al and O?
Al3+ O2-
Find the least common multiple!
24. What is the formula of a compound
containing ions of Al and O?
Al3+ O2-
Find the least common multiple!
3+ x 2 = 6+ 2- x 3 = 6-
25. What is the formula of a compound
containing ions of Al and O?
Al3+ O2-
Find the least common multiple!
3+ x 2 = 6+ 2- x 3 = 6-
So you need 2 Al3+ and 3 O2-
27. What is the formula of a compound
containing ions of Al and O?
28. What is the formula of a compound
containing ions of Al and O?
Al 3+ O2-
29. What is the formula of a compound
containing ions of Al and O?
Al 3+ O2-
Al2O3
30. What is the formula of a compound
containing ions of Al and O?
Al 3+ O2-
Al2O3
The charge on one ion becomes the
subscript for the other ion!
50. Simulation 5 Simulate the formation of
ionic compounds at the atomic level.
Simulation 5
52. • The coordination number of an ion
is the number of ions of opposite
charge that surround the ion in a
crystal.
53. • 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.
55. • In CsCl, each ion has a coordination
number of 8.
56. • 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.
57. Electricity is the directed
movement of charged particles.
To conduct electricity, a substance or
mixture must contain positive or
negative charges that can move freely.
60. 7.2 Section Quiz.
1. Which chemical formula is incorrect?
a. KF2
b. CaS
c. MgO
d. NaBr
61. 7.2 Section Quiz.
1. Which chemical formula is incorrect?
a. KF2
b. CaS
c. MgO
d. NaBr
62. 7.2 Section Quiz.
2. Ionic compounds can conduct an
electric current
a. only when melted.
b. when melted or dissolved in
water.
c. only when dissolved in
water.
d. when solid or melted.
63. 7.2 Section Quiz.
2. Ionic compounds can conduct an
electric current
a. only when melted.
b. when melted or dissolved in
water.
c. only when dissolved in
water.
d. when solid or melted.
64. 7.2 Section Quiz.
3. At room temperature, most ionic
compounds are
a. crystalline solids.
b. liquids.
c. gases.
d. soft, low melting-point
solids.
65. 7.2 Section Quiz.
3. At room temperature, most ionic
compounds are
a. crystalline solids.
b. liquids.
c. gases.
d. soft, low melting-point
solids.
Notas do Editor
Aluminum metal and the nonmetal bromine react to form an ionic solid, aluminum bromide.
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?
The beauty of crystalline solids, such as these, comes from the orderly arrangement of their component ions.
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.
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.
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?