Chapter 4
Compounds and Their Bonds
1

4.1
Octet Rule and Ions

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Ionic and Covalent Bonds
2

Atoms that are not noble gases form octets
 to become more stable
 by losing, gaining, or sharing valence electrons
 by forming ionic bonds or covalent bonds
Ionic bonds occur when atoms of one element lose valence electrons and the atoms of another element gain valence electrons.
Covalent bonds occur when nonmetal atoms share electrons to attain a noble gas arrangement.

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

The Octet Rule
3

An octet
• is eight valence electrons
• is associated with the stability of the noble gases
(except He)
The octet rule states that elements gain or lose electrons and become ions to attain noble gas arrangement. valence electrons
He 2
2
Ne 2, 8
8
Ar 2, 8, 8
8
Kr 2, 8, 14, 8
8
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Ionic and Covalent Bonds
4

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Metals Form Positive Ions
5

Metals form positive ions
 by a loss of their valence electrons
 with the electron configuration of the nearest noble gas
 that have fewer electrons than protons
Group 1A metals ion 1+
Group 2A metals ion 2+
Group 3A metals ion 3+

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Formation of Magnesium Ion, Mg2+
6

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Nonmetals Form Negative Ions
7

Nonmetals form negative ions:
 by a gain of valence electrons
 with the electron configuration of the nearest noble gas
 with fewer protons than electrons
Group 5A nonmetals ion 3−
Group 6A nonmetals ion 2−
Group 7A nonmetals ion 1−

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Formation of Chloride Ion, Cl−
8

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Formulas and Names of Common Ions
9

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Learning Check
10

Write the formula and symbol of an ion with 16 protons and 18 electrons. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Solution
11

Write the formula and symbol of an ion with 16 protons and 18 electrons. The element with 16 protons is sulfur, with the symbol S.
An ion of sulfur with 18 electrons gives sulfur a charge of 2−.
The sulfide ion is S2−.

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Ionic Charges from Group Numbers
12

Group

Charge

Group 1A1+
Group 2A2+
Group 3A3+

Positive Charges

Group 5A3−
Group 6A2−
Group 7A1−

Negative Charges

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Ionic Charges from Group Numbers
13

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition

Copyright © 2012 by Pearson Education, Inc.

Learning Check
14

Consider the elements calcium and chlorine.
A. Identify each as a metal or a nonmetal.
B. State the number of valence electrons for each.
C. State the number of electrons that must be lost or gained for each to acquire an octet.
D.