Transcript Document

Chapter 6 Lecture
Basic Chemistry
Fourth Edition
Chapter 6 Ionic and Molecular
Compounds
6.1 Ions: Transfer of Electrons
Learning Goal Write the
symbols for the simple ions of
the representative elements.
© 2014 Pearson Education, Inc.
Chapter 6 Readiness
Key Math Skills
• Using Positive and Negative Numbers in
Calculations (1.4B)
• Solving Equations (1.4D)
Core Chemistry Skills
• Writing Electron Configurations (5.4)
• Drawing Electron-Dot Symbols (5.6)
© 2014 Pearson Education, Inc.
Compounds
Most elements except for noble gases are found
in nature combined with other elements in
compounds.
Compounds form when electrons are transferred
or shared to give a stable electron configuration
to both atoms.
© 2014 Pearson Education, Inc.
Compounds
Atoms lose, gain, or share electrons in the form
of an ionic bond or covalent bond to obtain
an octet.
• Ionic bonds are formed when the valence
electrons of a metal are transferred to atoms of
nonmetals.
• Covalent bonds are formed when atoms of
nonmetals share their valence electrons.
© 2014 Pearson Education, Inc.
Ionic and Molecular Compounds
© 2014 Pearson Education, Inc.
Ionic and Molecular Compounds
© 2014 Pearson Education, Inc.
Positive Ions: Loss of Electrons
Ions, which have electrical charges, form when
atoms lose or gain electrons to form a stable
electron configuration.
• Because ionization energies of metals in
Group 1A (1), 2A (2), and 3A (13) are low,
metal atoms lose their valence electrons,
forming ions with a positive charge.
© 2014 Pearson Education, Inc.
Positive Ions: Loss of Electrons
A sodium atom (Na) will lose its 3s1 electron to
form a sodium ion (Na+).
Positively charged ions of metals are called
cations.
© 2014 Pearson Education, Inc.
Positive Ions: Loss of Electrons
Magnesium, a metal in Group 2A (2), obtains
a stable electron configuration by losing two
valence electrons, forming an ion with a
2+ charge.
© 2014 Pearson Education, Inc.
Negative Ions: Gain of Electrons
The ionization energy of a nonmetal atom in
Groups 5A (15), 6A (16), and 7A (17) is high.
Rather than lose electrons to form ions, a
nonmetal atom will gain one or more electrons to
obtain a stable electron configuration.
© 2014 Pearson Education, Inc.
Negative Ions: Gain of Electrons
An atom of chlorine with seven valence
electrons gains one electron to form an octet.
Because it now has 18 electrons and not
17 electrons, it becomes a chloride ion (Cl−)
with a charge of 1−.
Negatively charged ions of nonmetals are called
anions.
© 2014 Pearson Education, Inc.
Formula and Names of Some Common Ions
© 2014 Pearson Education, Inc.
Learning Check
Select the correct answer for aluminum.
A. The electron change to obtain an octet is
_____.
(1) loss of 3 e−(2) gain of 3 e− (3) gain of 5 e −
B. The charge of the aluminum ion is _____.
(1) 3− (2) 5−
(3) 3+
C. The symbol for the aluminum ion is _____.
(1) Al3+ (2) Al3– (3) Al+
© 2014 Pearson Education, Inc.
Solution
Select the correct answer for aluminum.
A. The electron change to obtain an octet is
_____. (1) loss of 3 e−
B.
The charge of the aluminum ion is _____.
(3) 3+
C. The symbol for the aluminum ion is _____.
(1) Al3+
© 2014 Pearson Education, Inc.
Ionic Charges from Group Numbers
We can use group numbers of representative
elements in the periodic
Group
Ion
table to determine their
Number
Charge
charges.
Group 1A (1)
1+
© 2014 Pearson Education, Inc.
Group 2A (2)
2+
Group 3A (13)
3+
Group 5A (15)
3−
Group 6A (16)
2−
Group 7A (17)
1−
Common Ions and Their Nearest
Noble Gases
Atoms lose or gain electrons to become like their
nearest noble gas.
© 2014 Pearson Education, Inc.
Learning Check
Select the correct answer for sulfur.
A. The group number for sulfur is _____.
B. The number of valence electrons in sulfur
is ____.
C. The change in electrons for an octet requires a
(1) loss of 2 e−
(2) gain of 2 e− (3) gain of 4
e−
D. The ionic charge of a sulfide ion is _____.
(1) 2+ (2) 2−
(3) 4−
© 2014 Pearson Education, Inc.
Solution
Select the correct answer for sulfur.
A. The group number for sulfur is 6A (16).
B. The number of valence electrons in sulfur
is six.
C. The change in electrons for an octet requires
a
(2) gain of 2 e−
D. The ionic charge of a sulfide ion is _____.
(2) 2−
© 2014 Pearson Education, Inc.
Chemistry Link to Health, Ions
Several ions in body fluids have important
physiological and metabolic functions.
© 2014 Pearson Education, Inc.