Chemistry
Ionic and Molecular Compounds
Ionic compounds are formed through the transfer of electrons between atoms, resulting in the formation of positively and negatively charged ions. These ions are held together by electrostatic forces, creating a lattice structure. In contrast, molecular compounds are formed through the sharing of electrons between atoms, resulting in the formation of molecules held together by covalent bonds.
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10 Key excerpts on "Ionic and Molecular Compounds"
eBook - PDF- Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2015(Publication Date)
- Openstax(Publisher)
When electrons are “shared” and molecules form, covalent bonds result. Covalent bonds are the attractive forces between the positively charged nuclei of the bonded atoms and one or more pairs of electrons that are located between the atoms. Compounds are classified as ionic or molecular (covalent) on the basis of the bonds present in them. Ionic Compounds When an element composed of atoms that readily lose electrons (a metal) reacts with an element composed of atoms that readily gain electrons (a nonmetal), a transfer of electrons usually occurs, producing ions. The compound formed by this transfer is stabilized by the electrostatic attractions (ionic bonds) between the ions of opposite charge present in the compound. For example, when each sodium atom in a sample of sodium metal (group 1) gives up one electron to form a sodium cation, Na + , and each chlorine atom in a sample of chlorine gas (group 17) accepts one electron to form a chloride anion, Cl − , the resulting compound, NaCl, is composed of sodium ions and chloride ions in the ratio Chapter 2 | Atoms, Molecules, and Ions 101 of one Na + ion for each Cl − ion. Similarly, each calcium atom (group 2) can give up two electrons and transfer one to each of two chlorine atoms to form CaCl 2 , which is composed of Ca 2+ and Cl − ions in the ratio of one Ca 2+ ion to two Cl − ions. A compound that contains ions and is held together by ionic bonds is called an ionic compound. The periodic table can help us recognize many of the compounds that are ionic: When a metal is combined with one or more nonmetals, the compound is usually ionic. This guideline works well for predicting ionic compound formation for most of the compounds typically encountered in an introductory chemistry course. However, it is not always true (for example, aluminum chloride, AlCl 3 , is not ionic). You can often recognize ionic compounds because of their properties.
eBook - PDF- Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2019(Publication Date)
- Openstax(Publisher)
When electrons are transferred and ions form, ionic bonds result. Ionic bonds are electrostatic forces of attraction, that is, the attractive forces experienced between objects of opposite electrical charge (in this case, cations and anions). When electrons are “shared” and molecules form, covalent bonds result. Covalent bonds are the attractive forces between the positively charged nuclei of the bonded atoms and one or more pairs of electrons that are located between the atoms. Compounds are classified as ionic or molecular (covalent) on the basis of the bonds present in them. 92 2 • Atoms, Molecules, and Ions Access for free at openstax.org Ionic Compounds When an element composed of atoms that readily lose electrons (a metal) reacts with an element composed of atoms that readily gain electrons (a nonmetal), a transfer of electrons usually occurs, producing ions. The compound formed by this transfer is stabilized by the electrostatic attractions (ionic bonds) between the ions of opposite charge present in the compound. For example, when each sodium atom in a sample of sodium metal (group 1) gives up one electron to form a sodium cation, Na + , and each chlorine atom in a sample of chlorine gas (group 17) accepts one electron to form a chloride anion, Cl − , the resulting compound, NaCl, is composed of sodium ions and chloride ions in the ratio of one Na + ion for each Cl − ion. Similarly, each calcium atom (group 2) can give up two electrons and transfer one to each of two chlorine atoms to form CaCl 2 , which is composed of Ca 2+ and Cl − ions in the ratio of one Ca 2+ ion to two Cl − ions. A compound that contains ions and is held together by ionic bonds is called an ionic compound. The periodic table can help us recognize many of the compounds that are ionic: When a metal is combined with one or more nonmetals, the compound is usually ionic.
eBook - PDF- Leo J. Malone, Theodore O. Dolter(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
Chapter 9 The Chemical Bond T his is our home as seen from far-out space. Its surface and atmosphere are composed of some free elements as well as Ionic and Molecular Compounds. We look deeper into the nature of compounds in this chapter. 275 Part A Chemical Bonds and the Nature of Ionic Compounds 9-1 Bond Formation and Representative Elements 9-2 Formation of Ions and Ionic Compounds Part B Chemical Bonds and the Nature of Molecular Compounds 9-3 The Covalent Bond MAKING IT REAL Nitrogen: From the Air to Proteins 9-4 Writing Lewis Structures 9-5 Resonance Structures 9-6 Formal Charge Part C The Distribution of Charge in Chemical Bonds 9-7 Electronegativity and Polarity of Bonds 9-8 Geometry of Simple Molecules 9-9 Polarity of Molecules MAKING IT REAL Enzymes—The Keys of Life SETTING THE STAGE Earth is a complex world of chemicals. Consider the air. It is composed of molecular elements—nitrogen and oxygen— as well as smaller quantities of the solitary atoms of noble gases—argon, helium, and neon. In addition there are trace amounts of several molecular compounds such as carbon di- oxide and water. The surface of Earth is largely composed of water containing dissolved compounds. The solid surface of Earth contains compounds of living things, rocks, and fossils. We will focus on two compounds that occur in nature and are necessary in life processes—salt and water. These two compounds are examples of the two basic types of com- pounds: ionic and molecular. Salt (specifically, sodium chlo- ride) is typical of ionic compounds. It is a hard, brittle solid with a high melting point. Water, however, is typical of many molecular compounds in that it is a liquid at or near room temperature. What is there about these two compounds that make them so distinct? Even though both are composed of just two elements, there actually is an important difference. Sodium chloride is a binary compound formed from a metal, sodium, and a nonmetal, chlorine.
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)
Bonding: General Concepts CHAPTER 3 3.1 Types of Chemical Bonds 3.2 Electronegativity 3.3 Ions: Electron Configurations and Sizes Predicting Formulas of Ionic Compounds Sizes of Ions 3.4 Partial Ionic Character of Covalent Bonds 3.5 The Covalent Chemical Bond: A Model Models: An Overview 3.6 The Localized Electron Bonding Model 3.7 Lewis Structures 3.8 Exceptions to the Octet Rule Odd-Electron Molecules 3.9 Resonance Formal Charge 3.10 Naming Simple Compounds Binary Ionic Compounds (Type I) Formulas from Names Binary Ionic Compounds (Type II) Ionic Compounds with Polyatomic Ions Binary Covalent Compounds (Type III) Acids The nudibranch uses a particular molecule (called an allomone) to defend itself against predators. (Manex Catalapiedra/Getty Images) 98 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. A s we examine the world around us, we find it to be composed almost entirely of compounds and mixtures of compounds: Rocks, coal, soil, petroleum, trees, and human bodies are all complex mixtures of chemical compounds in which different kinds of atoms are bound together. Substances composed of unbound atoms do exist in nature, but they are very rare. Examples are the argon in the atmosphere and the helium mixed with natural gas reserves. The manner in which atoms are bound together has a profound effect on chemical and physical properties. For example, graphite is a soft, slippery material used as a lubricant in locks, and diamond is one of the hardest materials known, valuable both as a gemstone and in industrial cutting tools.
eBook - PDF- Young, William Vining, Roberta Day, Beatrice Botch(Authors)
- 2017(Publication Date)
- Cengage Learning EMEA(Publisher)
Vasilyev/Shutterstock.com 5 Ionic and Covalent Compounds Unit Outline 5.1 Formation and Electron Configuration of Ions 5.2 Polyatomic Ions and Ionic Compounds 5.3 Covalent Compounds In This Unit… As we saw in Electron Configurations and the Properties of Atoms (Unit 4), metals have lower ionization energies than nonmetals, and non-metals have a greater affinity for electrons than do metals. We also saw that trends in ionization energy and electron affinity, along with trends in atomic size, are related to the electron configuration of atoms. In this unit, we explore the consequences of electron configurations and how they impact a chemical property of elements: the types of compounds (ionic or covalent) that elements form. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300 Unit 5 Ionic and Covalent Compounds 104 5.1 Formation and Electron Configuration of Ions 5.1a Coulomb’s Law Matter is made up of atoms and ions that experience both attractive and repulsive forces. The strength of the force between two charged particles together in any material is described by Coulomb’s law (Equation 5.1). According to this law, the force of attraction or repulsion between two charged species is directly proportional to the magnitude of the charge on the particles ( q A and q B in Equation 5.1) and inversely proportional to the square of the distance between the two particles ( r in Equation 5.1). F orce ~ 1 q A 21 q B 2 r 2 (5.1) For electrons, q 5 2 e , and for nuclei, q 5 1 Ze where e 5 magnitude of electron charge 1 1.6022 3 10 2 19 C 2 Z 5 nuclear charge 1 number of protons 2 r 5 distance between particles A and B Interactive Figure 5.1.1 shows a demonstration of Coulomb’s law using a gold leaf electroscope in which a narrow metal plate and a thin sheet of gold are connected to a conducting rod.
- 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- Douglas P. Heller, Carl H. Snyder(Authors)
- 2015(Publication Date)
- Wiley(Publisher)
Covalent compounds exist as discrete molecular units, as opposed to ionic compounds, which exist as a regularly ordered array (crystal lattice) of ions that extends out in space. 2. The atoms in the molecules of covalent compounds are held together by covalent bonds. In ionic com- pounds, the ions of the crystal lattice are held togeth- er by ionic bonds. 76 CHAPTER 3 Chemical Compounds (SVRP VDOW²XVHG IRU WKHUDSHXWLF EDWKV 6XOIDWH LRQ $OVR NQRZQ DV PDJQHVLXP VXOIDWH 0J62 0J + 2 2 2 2 6 – %LFDUERQDWH LRQ %DNLQJ VRGD ² XVHG LQ FRRNLQJ FOHDQLQJ DQG D YDULHW\ RI RWKHU SXUSRVHV $OVR NQRZQ DV VRGLXP ELFDUERQDWH 1D+&2 1D + 2²+ 2 2 & – +\GUR[LGH LRQ 0J + 0LON RI PDJQHVLD ² D VXVSHQVLRQ RI PDJQHVLXP K\GUR[LGH 0J2+ XVHG WR WUHDW LQGLJHVWLRQ DQG FRQVWLSDWLRQ + 2 – +\SRFKORULWH LRQ %OHDFK ² D VROXWLRQ RI VRGLXP K\SRFKORULWH 1D2&O 1D + &O 2 – 5JN 0 8BMLFS 5JN 0 8BMLFS 5JN 0 8BMLFS 5JN 0 8BMLFS electric charge. In the sulfate ion, SO 4 2− , for example, sulfur and oxygen atoms are connect- ed by covalent bonds, with the overall cluster of atoms carrying a negative charge. A variety of polyatomic ions occurs in everyday chemical substanc- es (see Table 3.4 and What a Chemist Sees). Looking back at the ionic compounds we’ve stud- ied, we see that they were all of the binary type, com- bining a metal with a nonmetal in some fixed proportion. Some ionic compounds contain poly- atomic ions. The atoms forming a polyatomic ion are bound together by covalent bonds, with the cluster as a whole bearing a positive or negative Common polyatomic ions Table 3.4 Name Formula Ammonium NH 4 + Bicarbonate HCO 3 – Carbonate CO 3 2– Hydroxide OH – Nitrate NO 3 – Nitrite NO 2 – Phosphate PO 4 3– Sulfate SO 4 2– 1. How is the covalent compound H 2 O structurally different from the ionic compound Na 2 O? 2. What are the molecular formula and molecular mass of cortisone, a covalent compound with 21 carbon atoms, 28 hydrogen, and 5 oxygen atoms in each molecule? 3. Why does sodium chloride not exist as a molecule? Sulfate ion O O O O S 2– polyatomic ion An ion made up of more than one atom. WHAT A CHEMIST SEES Everyday Products Containing Polyatomic Ions Many common household products contain ionic compounds made up of
eBook - PDF- Morris Hein, Susan Arena, Cary Willard(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
11.3 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. 11.4 The Covalent Bond: Sharing Electrons KEY TERMS: covalent bond Lewis structure polar covalent bond • 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. 11.5 Electronegativity KEY TERMS: electronegativity nonpolar covalent bond dipole • Electronegativity is the attractive force an atom has for shared electrons in a molecule or polyatomic ion. Chapter 11 Review Chapter 11 Review 257 • 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. • A molecule that is electrically asymmetrical has a dipole, resulting in charged areas within the molecule. H : Cl H Cl + δ - δ hydrogen chloride -δ +δ • 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. 11.6 Lewis Structures of Compounds Problem-Solving Strategy Writing a Lewis Structure 1. Obtain the total number of valence electrons to be used in the structure by adding the number of valence electrons in all the atoms in the molecule or ion.
eBook - PDFGeneral, Organic, and Biological Chemistry
An Integrated Approach
- Kenneth W. Raymond(Author)
- 2012(Publication Date)
- Wiley(Publisher)
This is less than the amount of salt in a McDonald’s Quarter Pounder with cheese (3383 mg), a Burger King Whopper (2594 mg), a Wendy’s Homestyle Chicken Fillet sandwich (2849 mg), or one Ken- tucky Fried Chicken origi- nal recipe chicken breast (2696 mg). ? When the atoms in an element or compound combine to form new compounds, chemical change has taken place. For example, when a piece of iron rusts (Figure 3.6), a chemical change has occurred because iron (an element) combines with oxygen (a dif- ferent element) to produce rust (a compound that is made from iron ions and oxygen ions). The chemical changes that an element or a compound undergo are called chemical properties. Any matter that consists only of an element or a compound is called a pure substance (Figure 3.7). Depending on how elements combine with one another, the compound formed will be either ionic or covalent. (As you continue reading Chapter 3, you will learn the meaning of these terms.) Mixtures are a combination of two or more pure sub- stances. Mixtures are a topic of Chapter 6. Ionic compounds are constructed from cations (positively charged ions) and anions (negatively charged ions). The simplest ionic compounds are binary (contain just two elements) and contain metal cations bonded to nonmetal anions. Sodium chloride, a binary ionic compound, contains Na + and Cl - , and the opposite charge on these ions provides the ionic bond that holds the compound together. Figure 3.8 shows the struc- ture of sodium chloride, which consists of a crystal lattice (array) of alternating cations and anions. In this lattice, each ion is surrounded by others of opposite charge. 98 CHAPTER 3 Compounds The formula of any ionic compound is a listing of the relative number of each type of ion that is present, with the cation listed before the anion. Sodium chloride, whose formula is NaCl, contains an equal number of Na + and Cl - ions. MgCl 2 is a binary ionic compound that has 2 Cl - for each Mg 2+ .
eBook - PDFChemistry
The Molecular Nature of Matter
- Neil D. Jespersen, Alison Hyslop(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
© SKrow/iStockphoto © SKrow/iStockphoto © skegbydave/iStockphoto Elements, Compounds, and the Periodic Table Chapter Outline 2.1 | The Periodic Table 2.2 | Metals, Nonmetals, and Metalloids 2.3 | Molecules and Chemical Formulas 2.4 | Chemical Reactions and Chemical Equations 2.5 | Ionic Compounds 2.6 | Nomenclature of Ionic Compounds 2.7 | Molecular Compounds 2.8 | Nomenclature of Molecular Compounds 2 63 I n this chapter we consider one of the most recognizable icons in all of science, the periodic table. Using two simple observations, the relative masses of the elements and the reactions they enter into, much of the known data about the elements was organized into logical rows and columns. Our chapter-opening photo has several smart phones, each displaying a type of list that you might like to keep. An app list arranges the apps in the order that you set, so they can be called up quickly. Your to-do list may be arranged by the importance of each task, and the playlist may be arranged based on the music you like. We will find that the chemists’ periodic table is another useful way to arrange information. From there, this chapter discusses the types of elements by classifying them in various ways. We finish the chapter by describing the use of chemical equations to ex- plain how chemicals react with each other and the systematic naming of simple chemical compounds. This Chapter in Context 2.1 | The Periodic Table When we study different kinds of substances, we find that some are elements and others are compounds. Among the compounds, some are composed of discrete molecules while others are ionic compounds, made up of atoms that have acquired electrical charges. Some elements, such as iron and chromium, have properties we associate with metals, whereas others, such as carbon and sulfur, do not have metallic properties and are said to be nonmetallic.
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