Chemistry
Ionic Bonding
Ionic bonding is a type of chemical bond that forms between ions of opposite charges. It occurs when one atom transfers electrons to another, resulting in the formation of positively and negatively charged ions. These ions are then attracted to each other due to their opposite charges, creating a strong bond between the atoms.
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10 Key excerpts on "Ionic Bonding"
eBook - PDF- Morris Hein, Susan Arena, Cary Willard(Authors)
- 2016(Publication Date)
- Wiley(Publisher)
An ionic bond is the attraction between oppositely charged ions. Ionic bonds are formed whenever one or more electrons are transferred from one atom to another. Metals, which have relatively little attraction for their valence electrons, tend to form ionic bonds when they combine with nonmetals. It’s important to recognize that substances with ionic bonds do not exist as molecules. In sodium chloride, for example, the bond does not exist solely between a single sodium ion and a single chloride ion. Each sodium ion in the crystal attracts six near-neighbor negative chloride ions; in turn, each negative chloride ion attracts six near-neighbor posi- tive sodium ions (see Figure 11.5). A metal will usually have one, two, or three electrons in its outer energy level. In reacting, metal atoms characteristically lose these electrons, attain the electron structure of a noble gas, and become positive ions. A nonmetal, on the other hand, is only a few electrons short of having a noble gas electron structure in its outer energy level and thus has a tendency to gain electrons. In reacting with metals, nonmetal atoms characteristically gain one to four electrons, attain the electron structure of a noble gas, and become negative ions. The ions 226 CHAPTER 11 • Chemical Bonds: The Formation of Compounds from Atoms formed by loss of electrons are much smaller than the corresponding metal atoms; the ions formed by gaining electrons are larger than the corresponding nonmetal atoms. The dimen- sions of the atomic and ionic radii of several metals and nonmetals are given in TABLE 11.3. P R A C T I C E 1 1 . 3 What noble gas structure is formed when an atom of each of these metals loses all its valence electrons? Write the formula for the metal ion formed. (a) K (b) Mg (c) Al (d) Ba Study the following examples. Note the loss and gain of electrons between atoms; also note that the ions in each compound have a noble gas electron structure.
eBook - PDF- Morris Hein, Susan Arena, Cary Willard(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
An ionic bond is the attraction between oppositely charged ions. Ionic bonds are formed whenever one or more electrons are transferred from one atom to another. Metals, which have relatively little attraction for their valence electrons, tend to form ionic bonds when they combine with nonmetals. It’s important to recognize that substances with ionic bonds do not exist as molecules. In sodium chloride, for example, the bond does not exist solely between a single sodium ion and a single chloride ion. Each sodium ion in the crystal attracts six near-neighbor negative chloride ions; in turn, each negative chloride ion attracts six near-neighbor positive sodium ions (see Figure 11.4). A metal will usually have one, two, or three electrons in its outer energy level. In react- ing, metal atoms characteristically lose these electrons, attain the electron structure of a noble gas, and become positive ions. A nonmetal, on the other hand, is only a few electrons short of having a noble gas electron structure in its outer energy level and thus has a ten- dency to gain electrons. In reacting with metals, nonmetal atoms characteristically gain one to four electrons, attain the electron structure of a noble gas, and become negative ions. The ions formed by loss of electrons are much smaller than the corresponding metal atoms; the ions formed by gaining electrons are larger than the corresponding nonmetal atoms. The dimensions of the atomic and ionic radii of several metals and nonmetals are given in Table 11.3. Note A cation is always smaller than its parent atom, whereas an anion is always larger than its parent atom.
eBook - PDFChemistry
An Atoms First Approach
- Steven Zumdahl, Susan Zumdahl, Donald J. DeCoste, , Steven Zumdahl, Steven Zumdahl, Susan Zumdahl, Donald J. DeCoste(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
▲ Molten NaCl conducts an electric current, indicating the presence of mobile Na 1 and Cl 2 ions. Ken O’Donoghue 110 CHAPTER 3 Bonding: General Concepts Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. exist. These results cannot necessarily be assumed to apply to the solid state, where the existence of ions is favored by the multiple ion interactions. Another complication in identifying ionic compounds is that many substances con- tain polyatomic ions. For example, NH 4 Cl contains NH 4 1 and Cl 2 ions, and Na 2 SO 4 contains Na 1 and SO 4 22 ions. The bonds within the ammonium (NH 4 1 ) and sulfate (SO 4 22 ) ions are covalent bonds. We will avoid these problems by adopting an operational definition of ionic com- pounds: Any compound that conducts an electric current when melted will be classi- fied as ionic. 3.5 The Covalent Chemical Bond: A Model Before we develop specific models for covalent chemical bonding, it will be helpful to summarize some of the concepts introduced in this chapter. Also recall from your pre- vious studies of chemistry that when we deal with atoms and molecules, the numbers involved are so large that we use the mole (6.022 × 10 23 units) to describe quantities of atoms, molecules, or bonds. This concept was reviewed in Section R.10. What is a chemical bond? Chemical bonds can be viewed as forces that cause a group of atoms to behave as a unit. Why do chemical bonds occur? There is no principle of nature that states that bonds are favored or disfavored.
eBook - PDFChemistry
The Molecular Nature of Matter
- Neil D. Jespersen, Alison Hyslop(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
365 This Chapter in Context In a chapter on chemical bonding, your thoughts might stray to glues, cements, pastes, and adhesive tapes shown in the opening photo. They are macroscopic versions of bonding objects together. We will investigate the bonding of atoms and ions at the molecular level in this chapter. Chemists were able to develop the bonding materials like the ones shown in this photo because of their understanding of the molecular level interactions. In Chapter 2, we classified substances into two broad categories, ionic compounds and molecular compounds. Ionic compounds, such as ordinary table salt, consist of anions and cations that bind to each other by electrostatic forces of attrac- tion. We also said that in molecular substances, such as water, the atoms are held to each other by the sharing of electrons. Now that you’ve learned about the electronic structures of atoms, we can explore the attractions between atoms or ions, called chemical bonds, in greater depth. Our goal is to gain some insight into the reasons certain combinations of atoms prefer electron transfer and the formation of ions (leading to Ionic Bonding), while other combinations bind by electron sharing (leading to covalent bonding). As with electronic structure, models of chemical bonding have also evolved, and in this chapter we introduce you to relatively simple theo- ries. Although more complex theories exist (some of which we describe in Chapters 9, 21, and 22), the basic concepts you will study in this chapter still find many useful applications in modern chemical thought.
eBook - PDFChemistry
The Molecular Nature of Matter
- James E. Brady, Neil D. Jespersen, Alison Hyslop(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
The Basics of Chemical Bonding Chapter Outline 8.1 | Energy Requirements for Bond Formation 8.2 | Ionic Bonding 8.3 | Octet Rule and Electron Configurations of Ions 8.4 | Lewis Symbols: Keeping Track of Valence Electrons 8.5 | Covalent Bonds 8.6 | Bond Polarity and Electronegativity 8.7 | Lewis Structures 8.8 | Resonance Structures 8.9 | Covalent Compounds of Carbon © Jim Zuckerman/Corbis The Empire State Building, an iconic structure of the New York City skyline, is a steel frame structure with an outer skin of stone. Just as the steel structure holds the 102-story building up, so do chemical bonds hold together the molecules that we will study in this chapter. 8 352 8.1 | Energy Requirements for Bond Formation 353 I n Chapter 2 we classified substances into two broad categories, ionic compounds and molecular compounds. Ionic compounds, such as ordinary table salt, consist of anions and cations that bind to each other by electrostatic forces of attraction. We also said that in molecular substances, such as water, the atoms are held to each other by the sharing of electrons. Now that you’ve learned about the electronic structures of atoms, we can explore the attractions between atoms or ions, called chemical bonds, in greater depth. Our goal is to gain some insight into the reasons certain combinations of atoms prefer electron transfer and the formation of ions (leading to Ionic Bonding), while other combinations bind by electron sharing (leading to covalent bonding). As with electronic structure, models of chemical bonding have also evolved, and in this chapter we introduce you to relatively simple theories. Although more complex theories exist (some of which we describe in Chapters 9, 21, and 22), the basic concepts you will study in this chapter still find many useful applications in modern chemical thought.
eBook - PDFFundamentals of Materials Science and Engineering
An Integrated Approach
- William D. Callister, Jr., David G. Rethwisch(Authors)
- 2022(Publication Date)
- Wiley(Publisher)
Secondary or physical forces and energies are also found in many solid materials; they are weaker than the primary ones but nonetheless influence the physical properties of some materials. The sections that follow explain the several kinds of primary and secondary interatomic bonds. bonding energy primary bond 2.6 | | PRIMARY INTERATOMIC BONDS Ionic Bonding Ionic Bonding is perhaps the easiest to describe and visualize. It is always found in compounds composed of both metallic and nonmetallic elements, elements situated at the horizontal extremities of the periodic table. Atoms of a metallic element easily give up their valence electrons to the nonmetallic atoms. In the process, all the atoms acquire stable or inert gas configurations (i.e., completely filled orbital shells) and, in addition, an electrical charge—that is, they become ions. Sodium chloride (NaCl) is the classic ionic material. A sodium atom can assume the electron structure of neon (and a net single positive charge with a reduction in size) by a transfer of its one va- lence 3s electron to a chlorine atom (Figure 2.13a). After such a transfer, the chlorine ion acquires a net negative charge, an electron configuration identical to that of argon; Ionic Bonding 2.6 Primary Interatomic Bonds 35 it is also larger than the chlorine atom. Ionic Bonding is illustrated schematically in Figure 2.13b. The attractive bonding forces are coulombic—that is, positive and negative ions, by virtue of their net electrical charge, attract one another. For two isolated ions, the attrac- tive energy E A is a function of the interatomic distance according to E A = − A __ r (2.9) Theoretically, the constant A is equal to A = 1 ____ 4 π ε 0 (|Z 1 |e)(|Z 2 |e) (2.10) Here ε 0 is the permittivity of a vacuum (8.85 × 10 −12 F/m), |Z 1 | and |Z 2 | are absolute values of the valences for the two ion types, and e is the electronic charge (1.602 × 10 −19 C).
- Morris Hein, Scott Pattison, Susan Arena, Leo R. Best(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
11.4 PREDICTING FORMULAS OF IONIC COMPOUNDS • Chemical compounds are always electrically neutral. • Metals lose electrons and nonmetals gain electrons to form compounds. • Stability is achieved (for representative elements) by attaining a noble gas electron configuration. 11.5 THE COVALENT BOND: SHARING ELECTRONS • Covalent bonds are formed when two atoms share a pair of electrons between them: • This is the predominant type of bonding in compounds. • True molecules exist in covalent compounds. • Overlap of orbitals forms a covalent bond. • Unequal sharing of electrons results in a polar covalent bond. 11.6 ELECTRONEGATIVITY • Electronegativity is the attractive force an atom has for shared electrons in a molecule or polyatomic ion. • Electrons spend more time closer to the more electronegative atom in a bond forming a polar bond. • The polarity of a bond is determined by the electronegativity difference between the atoms involved in the bond: • The greater the difference, the more polar the bond is. • At the extremes: • Large differences result in ionic bonds. • Tiny differences (or no difference) result(s) in a nonpolar covalent bond. C H A P T E R 1 1 R E V I E W KEY TERM ionization energy KEY TERM Lewis structure KEY TERM ionic bond KEY TERMS covalent bond polar covalent bond KEY TERMS electronegativity nonpolar covalent bond dipole 240 CHAPTER 11 • Chemical Bonds: The Formation of Compounds from Atoms • A molecule that is electrically asymmetrical has a dipole, resulting in charged areas within the molecule. −δ +δ H : Cl H Cl � � � � hydrogen chloride • If the electronegativity difference between two bonded atoms is greater than 1.7–1.9, the bond will be more ionic than covalent. • Polar bonds do not always result in polar molecules. 11.7 LEWIS STRUCTURES OF COMPOUNDS PROBLEM-SOLVING STRATEGY: Writing a Lewis Structure 1.
eBook - PDF- Leo J. Malone, Theodore O. Dolter(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
Transition metals also form positive ions, but for the most part these ions do not relate to a noble gas configuration. Some of these ions were discussed in Chapter 4. 280 CHAPTER 9 The Chemical Bond where all four of their outer electrons are involved, but the bonding in these compounds is best described by electron sharing rather than ion formation. For the most part, Group IVA nonmetals also bond by electron sharing rather than forming monatomic ions. Although there is some evidence for a C 4- ion with an octet of electrons, formation of such highly charged ions is an energetically unfavorable process. In Group VA, bismuth forms a +3 ion that does not follow the octet rule. 9-2.3 The Physical State of Ionic Compounds Much of the solid, hard surface of our Earth is composed of ionic compounds that tend to have high melting points and are usually hard and brittle. If we look into the basic structure of a crystal of table salt, we can see why. Ionic compounds do not exist as discrete molecular units with one Na + attached to one Cl - . As shown in Figure 9-2, each Na + is actually surrounded by six Cl - ions, and each Cl − ion is surrounded by six Na + ions in a three-dimensional array of ions called a lattice. Recall from Chapter 8 that cations are smaller than their parent atoms, whereas anions are larger. Thus, in most cases we can assume that the anion is larger than the cation. The lattice is held together strongly and rigidly by electrostatic interactions. These electrostatic attractions are known as ionic bonds. There are several other arrays of ions (lattices) used to accommodate both the size differences and varying ratios of cat- ions to anions found in all of the possible ionic compounds. For example, in CsCl both the Cs + and the Cl - are surrounded by eight oppositely charged ions.
eBook - PDFFundamentals of Materials Science and Engineering
An Integrated Approach
- William D. Callister, Jr., David G. Rethwisch(Authors)
- 2016(Publication Date)
- Wiley(Publisher)
• Bonding force and bonding energy are related to one another according to Equations 2.5a and 2.5b. • Attractive, repulsive, and net energies for two atoms or ions depend on interatomic separation per the schematic plot of Figure 2.10b. • From a plot of interatomic separation versus force for two atoms/ions, the equilibrium separation corresponds to the value at zero force. • From a plot of interatomic separation versus potential energy for two atoms/ions, the bonding energy corresponds to the energy value at the minimum of the curve. • For ionic bonds, electrically charged ions are formed by the transference of valence electrons from one atom type to another. • The attractive force between two isolated ions that have opposite charges may be computed using Equation 2.13. • There is a sharing of valence electrons between adjacent atoms when bonding is covalent. • Electron orbitals for some covalent bonds may overlap or hybridize. Hybridization of s and p orbitals to form sp 3 and sp 2 orbitals in carbon was discussed. Configurations of these hybrid orbitals were also noted. • With metallic bonding, the valence electrons form a “sea of electrons” that is uni- formly dispersed around the metal ion cores and acts as a form of glue for them. • Relatively weak van der Waals bonds result from attractive forces between electric dipoles, which may be induced or permanent. • For hydrogen bonding, highly polar molecules form when hydrogen covalently bonds to a nonmetallic element such as fluorine. Electrons in Atoms The Periodic Table Bonding Forces and Energies Primary Interatomic Bonds Secondary Bonding or van der Waals Bonding 44 • Chapter 2 / Atomic Structure and Interatomic Bonding • In addition to van der Waals bonding and the three primary bonding types, covalent– ionic, covalent–metallic, and metallic–ionic mixed bonds exist.
eBook - PDF- James Shipman, Jerry Wilson, Charles Higgins, Bo Lou, James Shipman(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
For ionic compounds to be electrically neutral, each formula unit must have an equal number of positive and negative charges. Thus, for the formulas for ionic compounds to be written correctly, the anions and cations must be shown in the smallest whole- number ratio that will equal zero charge. A simple way to determine the formula of an ionic compound is as follows: Use the anion charge (no sign) as the subscript for the cation and the cation charge (no sign) as the subscript for the anion. Convert the subscripts to the smallest whole-number ratio if necessary. This principle, which works for both monatomic and polyatomic ions, can be mastered by studying ●● Table 12.2, Example 12.4, and Confidence Exercise 12.4. The only other information you need to become adept at writing the formulas of ionic compounds is knowledge of the charges on common polyatomic ions (given in Table 11.6) and on ions of the representative elements (follow the pattern in Fig. 12.8). Very strong forces of attraction exist among oppositely charged ions, so ionic com- pounds are usually crystalline solids with high melting and boiling points. Recently, chemists have prepared ionic substances that have unusual properties due to their large, nonspherical cations that lead to especially weak Ionic Bonding. Often these ionic sub- stances are liquid at room temperature. Some of these ionic liquids promise to be “super- solvents,” and because of their environmental benefits, they may replace some organic solvents. Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
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