Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
64 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
7
Practice Problems
For each of the following atoms, write the electron configuration,
referring to the periodic table. Then write the formula of the ion
the atom is most likely to form and identify that ion as a cation
or an anion. Finally, write the electron configuration of the ion.
1. bromine (Br), element 35
2. gallium (Ga), element 31
3. sulfur (S), element 16
4. rubidium (Rb), element 37
7.2 The Formation and Nature of Ionic Bonds
To bond ionically, atoms must transfer valence electrons. An atom
that loses one or more electrons becomes a positive ion. An atom
that gains one or more electrons becomes a negative ion. The ionic
bond that forms is the electrostatic force holding the oppositely
charged ions together.
The total number of electrons lost must equal the total number
of electrons gained. The ratio of atoms that bond ionically must
therefore be such that overall electrical neutrality is maintained.
Example Problem 7-2
The Formation of an Ionic Compound
Atoms of magnesium (Mg, atomic number 12, group 2) and
chlorine (Cl, atomic number 17, group 17) bond to form the ionic
compound magnesium chloride. Use electron configurations and the
balance of charges to determine the ratio of magnesium and chlorine
atoms in magnesium chloride.
A neutral atom of magnesium has the electron configuration
1s 2 2s 2 2p 6 3s 2 , or, in abbreviated form, [Ne]3s 2 . Chlorine has the
electron configuration [Ne]3s 2 3p 5 . An atom of Mg would lose its
two valence electrons to form a 2ϩ ion and achieve the stable
electron configuration of a noble gas. An atom of Cl would gain
one electron to form a 1Ϫ ion. To achieve overall neutrality in the
compound, each Mg ion would require two Cl ions: (1 ϫ 2ϩ) ϩ
(2 ϫ 1Ϫ) ϭ 0. Thus, there is one Mg atom for every two Cl atoms
in magnesium chloride.
64 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
7
Practice Problems
For each of the following atoms, write the electron configuration,
referring to the periodic table. Then write the formula of the ion
the atom is most likely to form and identify that ion as a cation
or an anion. Finally, write the electron configuration of the ion.
1. bromine (Br), element 35
2. gallium (Ga), element 31
3. sulfur (S), element 16
4. rubidium (Rb), element 37
7.2 The Formation and Nature of Ionic Bonds
To bond ionically, atoms must transfer valence electrons. An atom
that loses one or more electrons becomes a positive ion. An atom
that gains one or more electrons becomes a negative ion. The ionic
bond that forms is the electrostatic force holding the oppositely
charged ions together.
The total number of electrons lost must equal the total number
of electrons gained. The ratio of atoms that bond ionically must
therefore be such that overall electrical neutrality is maintained.
Example Problem 7-2
The Formation of an Ionic Compound
Atoms of magnesium (Mg, atomic number 12, group 2) and
chlorine (Cl, atomic number 17, group 17) bond to form the ionic
compound magnesium chloride. Use electron configurations and the
balance of charges to determine the ratio of magnesium and chlorine
atoms in magnesium chloride.
A neutral atom of magnesium has the electron configuration
1s 2 2s 2 2p 6 3s 2 , or, in abbreviated form, [Ne]3s 2 . Chlorine has the
electron configuration [Ne]3s 2 3p 5 . An atom of Mg would lose its
two valence electrons to form a 2ϩ ion and achieve the stable
electron configuration of a noble gas. An atom of Cl would gain
one electron to form a 1Ϫ ion. To achieve overall neutrality in the
compound, each Mg ion would require two Cl ions: (1 ϫ 2ϩ) ϩ
(2 ϫ 1Ϫ) ϭ 0. Thus, there is one Mg atom for every two Cl atoms
in magnesium chloride.