chapter 4 Chemical Bonding-The Ionic Bond Model.pdf

3/31/2017 Chapter 4...

3/31/2017 Chapter 4 Chemical Bonding: The Ionic Bond Model Chapter 4. Chemical Bonding: The Ionic Bond Model Table of Contents Introduction to Inorganic Chemistry Instructor Dr. Upali Siriwardane (Ph.D. Ohio State) 4.1 Chemical Bonds E-mail: [email protected] 4.2 Valence Electrons and Lewis Symbols Office: 311 Carson Taylor Hall ; Phone: 318-257-4941; 4.3 The Octet Rule Office Hours: MWF 8:00-9:00 and 11:00-12:00; 4.4 The Ionic Bond Model TR 10:00-12:00 Contact me trough phone or e-mail if you have questions 4.5 The Sign and Magnitude of Ionic Charge Online Tests on Following days 4.6 Lewis Structures for Ionic Compounds March 24, 2017: Test 1 (Chapters 1-3) 4.7 Chemical Formulas for Ionic Compounds April 7, 2017 : Test 2 (Chapters 4-5) 4.8 The Structure of Ionic Compounds April 28, 2017: Test 3 (Chapters 6,7 &8) May 12, 2017 : Test 4 (Chapters 9, 10 &11) 4.9 Recognizing and Naming Binary Ionic Compounds May 15, 2017: Make Up Exam: Chapters 1-11) 4.10 Polyatomic Ions. 4.11 Chemical Formulas and Names for Ionic Compounds Containing Polyatomic Ions 1 Copyright © Cengage Learning. All rights reserved 2 Section 4.1 Section 4.1 Chemical Bonds Chemical Bonds A Chemical Bond Two Types of Chemical Bonds Attractive force that holds two atoms together in Ionic Bonds (metal + non-metal) Chapter 4 a more complex unit. Covalent Bonds (non-metal + non-metal) Chapter 5 Form as a result of interactions between Metallic Bonds (metal + metal) (not discussed) electrons found in the combining atoms. Copyright © Cengage Learning. All rights reserved 3 Copyright © Cengage Learning. All rights reserved 4 Section 4.1 Section 4.1 Chemical Bonds Chemical Bonds Ionic Bond Covalent Bond Chemical bond formed through the transfer of Chemical bond formed through the sharing of one or more electrons from one (metal) atom or one or more pairs of electrons between two non- group of atoms to another (non-metal) atom or metal atoms. group of atoms. Molecular Compound (Covalent Compound) Ionic Compound – A compound in which atoms are joined – A compound in which ionic bonds are present through covalent bonds. due to charged attractions between cations and anions. Copyright © Cengage Learning. All rights reserved 5 Copyright © Cengage Learning. All rights reserved 6 1  3/31/2017 Section 4.1 Section 4.1 Chemical Bonds Chemical Bonds Metallic Bond Bonding Chemical bond formed through the sharing of Most bonds are not 100% ionic or 100% one or more pairs of electrons between all covalent. atoms in a solid. Most bonds have some degree of both ionic and Metals: Metallic elements covalent character. Metallic properties are due to metallic bonding Alloys (Metallic compounds) – A compound in which atoms are joined through metallic bonds. Copyright © Cengage Learning. All rights reserved 7 Copyright © Cengage Learning. All rights reserved 8 Section 4.1 Section 4.2 Chemical Bonds Valence Electrons and Lewis Symbols Two Fundamental Concepts Valence Electron 1. Not all electrons in an atom participate in An electron in the outermost electron shell of a bonding. Those that participate are called representative element or noble-gas element. valence electrons. In these representative elements or nobel gases 2. Certain arrangements of electrons are more the valence electrons are found in either s or p stable than others, as is explained by the octet subshells. rule. Copyright © Cengage Learning. All rights reserved 9 Copyright © Cengage Learning. All rights reserved 10 Section 4.2 Section 4.2 Valence Electrons and Lewis Symbols Valence Electrons and Lewis Symbols Lewis Symbols for Selected Representative and Noble-Gas Lewis Symbol Elements Chemical symbol of an element surrounded by dots equal in number to the number of valence electrons present in atoms of the element. Copyright © Cengage Learning. All rights reserved 11 Copyright © Cengage Learning. All rights reserved 12 2  3/31/2017 Section 4.2 Section 4.2 Valence Electrons and Lewis Symbols Valence Electrons and Lewis Symbols Concept Check Concept Check Determine the number of valence electrons in Determine the number of valence electrons in each of the following elements: each of the following elements: Ca Ca 2 valence electrons (4s2) Se Se 6 valence electrons (4s24p4) C C 4 valence electrons (2s22p2) Copyright © Cengage Learning. All rights reserved 13 Copyright © Cengage Learning. All rights reserved 14 Section 4.2 Section 4.2 Valence Electrons and Lewis Symbols Valence Electrons and Lewis Symbols Three Important Generalizations About Valence Electrons Concept Check Write Lewis symbols for the following 1. Representative elements in the same group elements: have the same number of valence electrons. 2. The number of valence electrons for O representative elements is the same as the Roman numeral periodic-table group number. P 3. The maximum number of valence electrons for any element is eight. F Copyright © Cengage Learning. All rights reserved 15 Copyright © Cengage Learning. All rights reserved 16 Section 4.2 Section 4.3 Valence Electrons and Lewis Symbols The Octet Rule Concept Check Certain arrangements of valence electrons are Write Lewis symbols for the following more stable than others. elements: The valence electron configurations of the noble gases are considered the most stable of all O O valence electron configurations. P P F F Copyright © Cengage Learning. All rights reserved 17 Copyright © Cengage Learning. All rights reserved 18 3  3/31/2017 Section 4.3 Section 4.4 The Octet Rule The Ionic Bond Model Octet Rule (G.N. Lewis) Ion In forming compounds, atoms of elements lose, An atom (or group of atoms) that is electrically gain, or share electrons in such a way as to charged as a result of the loss or gain of produce a noble-gas electron configuration for electrons. each of the atoms involved. If an atom gains one or more electrons, it becomes a negatively charged ion (anion). If an atom loses one or more electrons, it becomes a positively charged ion (cation). Copyright © Cengage Learning. All rights reserved 19 Copyright © Cengage Learning. All rights reserved 20 Section 4.4 Section 4.4 The Ionic Bond Model The Ionic Bond Model Concept Check Give the chemical symbol for each of the following ions. Isoelectronic to Ne a) The ion formed when a potassium atom loses one electron. b) The ion formed when a sulfur atom gains two electrons. Isoelectronic to Ar Copyright © Cengage Learning. All rights reserved 21 Copyright © Cengage Learning. All rights reserved 22 Section 4.4 Section 4.5 The Ionic Bond Model The Sign and Magnitude of Ionic Charge Concept Check Atoms tend to gain or lose electrons until they Give the chemical symbol for each of the have obtained an electron configuration that is following ions. the same as that of a noble gas.  Example: K+ (1s22s22p63s23p6) a) The ion formed when a potassium atom loses one  Lost one electron to obtain electron configuration electron. for Ar (1s22s22p63s23p6). K+ b) The ion formed when a sulfur atom gains two electrons. S2– Copyright © Cengage Learning. All rights reserved 23 Copyright © Cengage Learning. All rights reserved 24 4  3/31/2017 Section 4.5 Section 4.5 The Sign and Magnitude of Ionic Charge The Sign and Magnitude of Ionic Charge 1. Metal atoms containing one, two, or three 2. Nonmetal atoms containing five, six, or seven valence electrons tend to lose electrons to valence electrons tend to gain electrons to acquire a noble-gas electron configuration. acquire a noble-gas electron configuration. + charge = group # - charge = 8 – group # Group Charge Group Charge IA 1+ VIIA 1– IIA 2+ VIA 2– IIIA 3+ VA 3– Copyright © Cengage Learning. All rights reserved 25 Copyright © Cengage Learning. All rights reserved 26 Section 4.5 Section 4.5 The Sign and Magnitude of Ionic Charge The Sign and Magnitude of Ionic Charge Isoelectronic Species 3. Elements in Group IVA occupy unique positions A series of ions/atoms containing the same relative to the noble gases (could gain or lose number and configuration of electrons. four electrons). Eg. C and Si O2-, F-, Ne, Na+, Mg2+, and Al3+ 1s22s22p6 Copyright © Cengage Learning. All rights reserved 27 Copyright © Cengage Learning. All rights reserved 28 Section 4.5 Section 4.5 The Sign and Magnitude of Ionic Charge The Sign and Magnitude of Ionic Charge Isoelectronic Species Mg2+ and Ne Concept Check Choose an alkali metal, an alkaline earth metal, a noble gas, and a halogen so that they constitute an isoelectronic series when the metals and halogen are written as their most stable ions. What is the electron configuration for each species? Determine the number of electrons for each species. Determine the number of protons for each species. Copyright © Cengage Learning. All rights reserved 29 Copyright © Cengage Learning. All rights reserved 30 5  3/31/2017 Section 4.6 Section 4.6 Lewis Structures for Ionic Compounds Lewis Structures for Ionic Compounds Formation of an Ionic Compound Lewis Structure Ion formation requires the presence of two Combination of Lewis symbols that represents elements: either the transfer or the sharing of electrons in – A metal that can donate electrons. chemical bonds. – A non-metal that can accept electrons. The electrons lost by the metal are the same ones gained by the nonmetal. The positive and negative ions simultaneously formed from such electron transfer attract one another. Copyright © Cengage Learning. All rights reserved 31 Copyright © Cengage Learning. All rights reserved 32 Section 4.6 Section 4.6 Lewis Structures for Ionic Compounds Lewis Structures for Ionic Compounds The Reaction Between Sodium and Chlorine The Reaction Between Sodium and Oxygen Core [ Ne] [Ar] Copyright © Cengage Learning. All rights reserved 33 Copyright © Cengage Learning. All rights reserved 34 Section 4.6 Section 4.7 Lewis Structures for Ionic Compounds Chemical Formulas for Ionic Compounds The Reaction Between Calcium and Chlorine Ionic compounds are always neutral; no net charge is present. The ratio in which positive and negative ions combine is the ratio that achieves charge neutrality for the resulting compound. Charges on ions determines the subscripts in the formula Eg. Na1+ O2- gives Na2O Copyright © Cengage Learning. All rights reserved 35 Copyright © Cengage Learning. All rights reserved 36 6  3/31/2017 Section 4.7 Section 4.7 Chemical Formulas for Ionic Compounds Chemical Formulas for Ionic Compounds Writing Chemical Formulas for Ionic Compounds Example 1. The symbol for the positive ions is always Compound formed between Li+ and O2– written first. – Need two Li+ to balance out the 2- charge on 2. The charges on the ions that are present are oxygen. not shown in the formula. Formula is Li2O. 3. The subscripts in the formula give the combining ratio for the ions. Copyright © Cengage Learning. All rights reserved 37 Copyright © Cengage Learning. All rights reserved 38 Section 4.7 Section 4.7 Chemical Formulas for Ionic Compounds Chemical Formulas for Ionic Compounds Concept Check Concept Check Determine the chemical formula for the Determine the chemical formula for the compound that is formed when each of the compound that is formed when each of the following pairs of ions interact. following pairs of ions interact. Ba2+ and Cl– Ba2+ and Cl– BaCl2 Fe3+ and O2– Fe3+ and O2– Fe2O3 Pb4+ and O2– Pb4+ and O2– PbO2 Copyright © Cengage Learning. All rights reserved 39 Copyright © Cengage Learning. All rights reserved 40 Section 4.8 Section 4.8 The Structure of Ionic Compounds The Structure of Ionic Compounds Solid Ionic Compounds (ionic lattices). Sodium Chloride (NaCl) Consists of positive and negative ions arranged in such a way that each ion is surrounded by nearest neighbors of the opposite charge. Any given ion is bonded by electrostatic attractions to all the other ions of opposite charge immediately surrounding it. Copyright © Cengage Learning. All rights reserved 41 Copyright © Cengage Learning. All rights reserved 42 7  3/31/2017 Section 4.8 Section 4.8 The Structure of Ionic Compounds The Structure of Ionic Compounds Formula Unit Cross-Section of NaCl Smallest whole-number repeating ratio of ions present in an ionic compound that results in charge neutrality. Chemical formulas for ionic compounds represent the simplest ratio of ions present. Eg. Ca2+ O2- gives Ca2O2 becomes CaO Copyright © Cengage Learning. All rights reserved 43 Copyright © Cengage Learning. All rights reserved 44 Section 4.9 Section 4.9 Recognizing and Naming Binary Ionic Compounds Recognizing and Naming Binary Ionic Compounds Naming Compounds Naming Ionic Compounds Binary Compounds: The full name of the metallic element is  Composed of two elements given first, followed by a separate word  Ionic and covalent compounds included containing the stem of the nonmetallic Binary Ionic Compounds: element name and the suffix –ide.  Metal-nonmetal  Metal is always present as the positive ion, and the nonmetal is always present as the negative ion. Copyright © Cengage Learning. All rights reserved 45 Copyright © Cengage Learning. All rights reserved 46 Section 4.9 Section 4.9 Recognizing and Naming Binary Ionic Compounds Recognizing and Naming Binary Ionic Compounds Names of Selected Common Nonmetallic Ions Examples KCl Potassium chloride MgBr2 Magnesium bromide CaO Calcium oxide Copyright © Cengage Learning. All rights reserved 47 Copyright © Cengage Learning. All rights reserved 48 8  3/31/2017 Section 4.9 Section 4.9 Recognizing and Naming Binary Ionic Compounds Recognizing and Naming Binary Ionic Compounds Naming Ionic Compounds (for Metals with Variable Charges) Examples Metals in these compounds form more than one type of positive charge. CuBr Copper(I) bromide Charge on the metal ion must be specified. Roman numeral indicates the charge of the FeS Iron(II) sulfide metal cation (positively charged ion). Transition metal cations usually require a PbO2 Lead(IV) oxide Roman numeral. Copyright © Cengage Learning. All rights reserved 49 Copyright © Cengage Learning. All rights reserved 50 Section 4.9 Section 4.9 Recognizing and Naming Binary Ionic Compounds Recognizing and Naming Binary Ionic Compounds Metallic Elements with a Fixed Ionic Charge Exercise Name each of the following compounds: K2S Fe2O3 CoCl2 Copyright © Cengage Learning. All rights reserved 51 Copyright © Cengage Learning. All rights reserved 52 Section 4.9 Section 4.10 Recognizing and Naming Binary Ionic Compounds Polyatomic Ions Exercise Polyatomic Ion Ion formed from a group of atoms (held Name each of the following compounds: together by covalent bonds) through loss or gain of electrons. K2S potassium sulfide Fe2O3 iron(III) oxide CoCl2 cobalt(II) chloride Copyright © Cengage Learning. All rights reserved 53 Copyright © Cengage Learning. All rights reserved 54 9  3/31/2017 Section 4.10 Section 4.10 Polyatomic Ions Polyatomic Ions Polyatomic Ion Polyatomic Ions. Must be memorized (see Table 4.3 on pg. 99 in text). Examples of compounds containing polyatomic ions: NaOH Sodium hydroxide Mg(NO3)2 Magnesium nitrate (NH4)2SO4 Ammonium sulfate Copyright © Cengage Learning. All rights reserved 55 Copyright © Cengage Learning. All rights reserved 56 Section 4.10 Section 4.10 Polyatomic Ions Polyatomic Ions Generalizations Generalizations 1. Most of the polyatomic ions have a negative 3. A number of –ate, –ite pairs of ions exist. The – charge. ate ion always has one more oxygen atom than 2. Two of the negatively charged polyatomic ions, the –ite ion. Both the –ate and –ite ions of a pair OH– and CN–, have names ending in –ide and carry the same charge. the rest of them have names ending in either – 4. A number of pairs of ions exist wherein one ate or –ite. member of the pair differs from the other by having a hydrogen atom present. In such pairs, the charge on the ion that contains hydrogen is always 1 less than that on the other ion. Copyright © Cengage Learning. All rights reserved 57 Copyright © Cengage Learning. All rights reserved 58 Section 4.11 Section 4.11 Chemical Formulas and Names for Ionic Compounds Containing Polyatomic Ions Chemical Formulas and Names for Ionic Compounds Containing Polyatomic Ions Exercise Determined in the same way as those for ionic compounds that contain Which of the following compounds is named monatomic ions. incorrectly? The positive and negative charges present must add to zero. a) KNO3 potassium nitrate  Na+ and OH– form NaOH. b) TiO2 titanium(II) oxide  Mg2+ and NO3– form Mg(NO3)2. c) Sn(OH)4 tin(IV) hydroxide d) (NH4)2SO3 ammonium sulfite  NH4+ and SO42– form (NH4)2SO4. e) CaCrO4 calcium chromate Copyright © Cengage Learning. All rights reserved 59 Copyright © Cengage Learning. All rights reserved 60 10  3/31/2017 Section 4.11 Chemical Formulas and Names for Ionic Compounds Containing Polyatomic Ions Exercise Which of the following compounds is named incorrectly? a) KNO3 potassium nitrate b) TiO2 titanium(II) oxide c) Sn(OH)4 tin(IV) hydroxide d) (NH4)2SO3 ammonium sulfite e) CaCrO4 calcium chromate titanium(IV) oxide Copyright © Cengage Learning. All rights reserved 61 11