Chapter 6 Lecture Basic Chemistry Fourth Edition Chapter
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. 4 B) • Solving Equations (1. 4 D) 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 1 A (1), 2 A (2), and 3 A (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 3 s 1 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 2 A (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 5 A (15), 6 A (16), and 7 A (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) Al 3+ (2) Al 3– (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) Al 3+ © 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 1 A (1) 1+ © 2014 Pearson Education, Inc. Group 2 A (2) 2+ Group 3 A (13) 3+ Group 5 A (15) 3− Group 6 A (16) 2− Group 7 A (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 6 A (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.
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