Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
65
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
7
Practice Problems
Write the electron configurations, in abbreviated form, for the
atoms in each pair, referring to the periodic table as necessary.
Then determine the ratio of the atoms in the ionic compound
formed in each case.
5. aluminum (Al) and fluorine (F)
6. lithium (Li) and oxygen (O)
7. beryllium (Be) and selenium (Se)
8. gallium (Ga) and sulfur (S)
Properties of ionic compounds and lattice energy In a solid
ionic compound, the positive ions are surrounded by negative ions,
and the negative ions by positive ions. The resulting structure is
called a crystal lattice and contains a regular, repeating, threedimensional arrangement of ions. This arrangement, which involves
strong attraction between oppositely charged ions, tends almost
always to produce certain properties, such as high melting and
boiling points and brittleness. Ionic compounds are always nonconductors of electricity when solid but good conductors when
melted. They also act as electrolytes, substances that conduct electric current when dissolved in water. The combination of these
conductivity characteristics is a very good identifier of ionic compounds, although each characteristic separately is not very reliable.
The energy required to separate one mole of the ions of an ionic
compound is called lattice energy, which is expressed as a negative
quantity. The greater (that is, the more negative) the lattice energy is,
the stronger is the force of attraction between the ions. Lattice
energy tends to be greater for more-highly-charged ions and for
small ions than for ions of lower charge or large size.
Practice Problems
9. On the basis of the properties of the following “unknowns,”
classify each as either ionic or not ionic.
a. conducts electricity when solid
b. conducts electricity when liquid and has a low melting point
c. has a high boiling point and shatters when hammered
d. has a high melting point and conducts electricity when
dissolved in water
▲
Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
65
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
7
Practice Problems
Write the electron configurations, in abbreviated form, for the
atoms in each pair, referring to the periodic table as necessary.
Then determine the ratio of the atoms in the ionic compound
formed in each case.
5. aluminum (Al) and fluorine (F)
6. lithium (Li) and oxygen (O)
7. beryllium (Be) and selenium (Se)
8. gallium (Ga) and sulfur (S)
Properties of ionic compounds and lattice energy In a solid
ionic compound, the positive ions are surrounded by negative ions,
and the negative ions by positive ions. The resulting structure is
called a crystal lattice and contains a regular, repeating, threedimensional arrangement of ions. This arrangement, which involves
strong attraction between oppositely charged ions, tends almost
always to produce certain properties, such as high melting and
boiling points and brittleness. Ionic compounds are always nonconductors of electricity when solid but good conductors when
melted. They also act as electrolytes, substances that conduct electric current when dissolved in water. The combination of these
conductivity characteristics is a very good identifier of ionic compounds, although each characteristic separately is not very reliable.
The energy required to separate one mole of the ions of an ionic
compound is called lattice energy, which is expressed as a negative
quantity. The greater (that is, the more negative) the lattice energy is,
the stronger is the force of attraction between the ions. Lattice
energy tends to be greater for more-highly-charged ions and for
small ions than for ions of lower charge or large size.
Practice Problems
9. On the basis of the properties of the following “unknowns,”
classify each as either ionic or not ionic.
a. conducts electricity when solid
b. conducts electricity when liquid and has a low melting point
c. has a high boiling point and shatters when hammered
d. has a high melting point and conducts electricity when
dissolved in water
▲