2 There are three types of strong bonds: Ionic Covalent Metallic Some substances contain both covalent and ionic bonding or an intermediate.
4 4.1 Ionic bonding Ionic bonding is an electrostatic attraction between oppositely charged ions.
5 One ore more electrons are transferred from the outer shell of one atom to the outer shell of another atom. The charge of an ion depends on the number of electrons the atom needed to loose or gain to achieve a full outer shell. 2 Na(s) + F2 (g) 2 NaF (s)
6 The electrons are shown in pairs, because each pair of electrons occupies an orbital. The successive energy levels in the atoms and ions are shown getting closer together. The radius of a sodium atom is approximately twice that of a chlorine atom. The radius of a sodium ion is approximately half that of a sodium atom. The radius of a chlorine ion is approximately twice that of a chlorine atom.
7 Cations If an atom loses e-, it becomes a positively charged ion. Group 1: Group 2: Group 3 Transition metals can form more than one ion, for example Cu+ and Cu2+, Fe2+ and Fe3+
8 Anions If an atom gains one or more e-, it becomes a negatively charged ion. Group 15: Group 16: Group 17:
9 Polyatomic ions
10 Ionic compounds Between metals (electropositive elements) and nonmetals (elements with high electronegativity). The difference in electronegativity values needs to be greater than about 1.8.
11 Formulas of ionic compounds The overall charge of the compound must be zero. Ex. CaF2
12 Lattice When an ionic compound is formed, the ions are packed in an organized crystalline structure, a lattice. The sum of all the electrostatic attractions between the oppositely charged ions is called the lattice energy.
13 The lattice energy has a high value and this energy is released when the ionic compound is formed. e.g. the formation of NaCl from Na(s) and Cl2(g) is an exothermic reaction. The value of lattice energy depends on: The charge of the ions The size of the ions The higher the value of lattice energy, the more stable is the ionic compound.
14 Physical properties Melting: The crystal structure is broken down, but there are still some attractive forces between the particles. Boiling: The attractive forces between the particles are completely broken. The stronger the bonds, the higher the boiling point.
15 Properties of ionic compounds High melting and boiling points because of strong attractive forces between the ions in the lattice (mp of Na 801º C) Conducts electricity when molten or dissolved in water. When a salt dissolves, new bonds are formed between the water molecules and the ions. This process is called hydration and the ions are said to be hydrated.
16 4.2 Covalent bonding Covalent bonding is the electrostatic attraction between a pair of electrons and positively charged nuclei.
17 Multiple covalent bonds Single bond: One shared electron pair with one electron from each atom. Double bond: Two shared electron pairs with two electrons from each atom. Triple bond: Three shared electron pairs with three electrons from each atom.
18 The more pairs of electrons there are in a covalent bond: - the shorter the bond length - the stronger the bond
19 Polarity of molecules
20 Molecules with polar bonds can be non-polar if they are symmetrical, that is if the central atom is symmetrically surrounded by identical atoms. In carbon dioxide the dipoles are exactly opposite in direction and cancel each other. O=C=O
21 Non-polar molecules In a chlorine molecule, the difference in electronegativities of the atoms is 0. This means that the electronpair in the covalent bond is on average shared EQUALLY between the 2 chlorine atoms. The bond is called a non-polar bond, thus making the molecule a non-polar molecule.
22 Polar molecules In hydrochloric acid, the difference in electronegativities is 1.0. The more electronegative chlorine atom draws the bonding pair of electrons towards itself and becomes negatively charged. The hydrogen atom then becomes positively charged. The bond is polar and the molecule has a dipole moment.
24 4.3 Covalent structures Lewis symbols show the number of valence electrons of an element represented ass either dots or crosses.
26 Drawing Lewis structures of molecules
27 Draw the Lewis structures for: a) O2 b) N2 c) CO2 d) HCN
28 Shapes of molecules and ions The shape of a molecule or ion can be predicted by the valence shell electron pair repulsion theory (VSEPR). The theory states that electron pairs (= electron domains) repel each other, and are therefore located as far away from each other as possible. The order of repulsion strength is: lone pair-lone-pair > lone pair-bond pair > bond pair-bond pair
29 If one or more of the negative charge centres is a nonbonding pair, this will influence the final shape of the molecule. e.g NH3 and H2O
31 Resonance structures For some molecules it is possible to write more than one correct Lewis structure. These structures are called resonance structures and true structure is an intermediate form known as a resonance hybrid.
32 Ex. All of the C-C bonds in benzene have the same bond length:
33 Coordinate covalent bonds In coordinate covalent bonds (dative covalent bonds) the shared pair of electrons comes from the same atom.
34 Covalent network solids Pure carbon has several different structural forms: These forms have different physical properties and they are called allotropes. Allotropes are crystalline forms of the same element, in which the atoms are bonded differently.
36 Silicon Tetrahedral arrangement
37 Silicon dioxide, SiO2 (quartz) Strong Insoluble in water High melting point Non-conductor of electricity
38 A common impure form of silicon dioxide is sand, which is colored yellow by the presence of iron (III) oxide.
39 Metallic bonding Delocalized valence electrons move freely through the metal. The attraction between these electrons and the cations holds the piece of metal intact.
40 Electrical conductivity The delocalization electrons enables free movement in response to electric fields.
41 Thermal conductivity Tight packing of cations and delocalized electrons transmit kinetic energy rapidly.
42 Malleability Individual atoms are not held to any other specific atoms, hence atoms slip easily past one another.
44 Intramolecular forces: - holds the atoms together within a molecule - affects molecular geometry and reactivity Intermolecular forces: - between the molecules within a compound - affects melting and boiling points
46 London forces (dispersion forces) Attractive forces that exist between ALL atoms and molecules. These forces are only temporary and very weak. Compounds that only have London forces have very low boiling points (they are gaseous at room temperature)
47 Factors that affect the magnitude of the London forces 1. Number of electrons in an atom The more electrons, the stronger the London forces. The more electrons, the further they are from the nucleus = less attraction the electron cloud is more easily polarized
48 2. Size of the electron cloud - The longer the carbon chain, the larger the electron cloud the stronger the London forces and the higher the boiling point
49 3. Shapes of molecules - The more contact area for the molecules, the stronger the forces.
50 Van der Waal s forces are due to the motions of electrons, which causes temporary dipoles. These forces generally increase in strength as the number of electrons in a molecule increases or if the surface area between the molecules increases. These forces are so weak that non-polar molecules have low boiling-points (many of them are gases at room temperature).
51 Dipole- dipole bonding Between permanent dipoles The negative pole of one polar molecule is attracted to the positive pole of another polar molecule.
52 Hydrogen bonding In molecules where hydrogen is directly bonded to a small highly electronegative element such as oxygen, nitrogen or fluorine.
53 Small molecules can have surprisingly high boiling points due to hydrogen bonds.
54 The lattice structure of ice
55 14.1 Further aspects of covalent bonding and structure (HL) The octet is the most common electron arrangement because of its stability. Exceptions: a) Fewer electrons (incomplete octet) if the central atom is a small atoms, e.g. Be and B b) More than eight electrons (expanded octet) if the central atom is a 3rd row element or below, e.g. P and S
56 Species with five negative charge centres If a molecule has five charge centres and they all are bonding electrons, the shape is triangular bipyramidal.
57 If one or more of these five negative charge centres is a non-bonding pair, this will influence the final shape of the molecule. One: Tetrahedron Two: T-shaped Three: Linear ClF3 I3-
58 Species with six negative charge centres Molecules with six charged centres that are all bonding have an octahedral shape, e.g. SF6. One non-bonding pair: square pyramidal BrF 5 Two non-bonding pairs: square planar XeF4
59 Formal Charge Formal charges are assigned to atoms that have an abnormal number of bonds. Formal charge Ex. For the nitrogen in ammonium: formal charge = 5-8/2 0 = +1
Chapter 11 Chemical Bonds: The Formation of Compounds from Atoms 1 11.1 Periodic Trends in atomic properties 11.1 Periodic Trends in atomic properties design of periodic table is based on observing properties
CHAPTER EIGHT BNDING: GENERAL CNCEPT or Review 1. Electronegativity is the ability of an atom in a molecule to attract electrons to itself. Electronegativity is a bonding term. Electron affinity is the
CHAPTER NOTES CHAPTER 16 Covalent Bonding Goals : To gain an understanding of : NOTES: 1. Valence electron and electron dot notation. 2. Stable electron configurations. 3. Covalent bonding. 4. Polarity
CHAPTER 6 Chemical Bonding SECTION 1 Introduction to Chemical Bonding OBJECTIVES 1. Define Chemical bond. 2. Explain why most atoms form chemical bonds. 3. Describe ionic and covalent bonding.. 4. Explain
EXPERIMENT 17 : Lewis Dot Structure / VSEPR Theory Materials: Molecular Model Kit INTRODUCTION Although it has recently become possible to image molecules and even atoms using a high-resolution microscope,
AP Chemistry A. Allan Chapter 8 Notes - Bonding: General Concepts 8.1 Types of Chemical Bonds A. Ionic Bonding 1. Electrons are transferred 2. Metals react with nonmetals 3. Ions paired have lower energy
Introduction Laboratory 11: Molecular Compounds and Lewis Structures Molecular compounds are formed by sharing electrons between non-metal atoms. A useful theory for understanding the formation of molecular
Name Date lass APTER 6 REVIEW hemical Bonding SETIN 1 SRT ANSWER Answer the following questions in the space provided. 1. a A chemical bond between atoms results from the attraction between the valence
Molecular and VSEPR We gratefully acknowledge Portland ommunity ollege for the use of this experiment. Objectives To construct molecular models for covalently bonded atoms in molecules and polyatomic ions
Chemistry I ATOMIC BONDING PRACTICE QUIZ Mr. Scott Select the best answer. 1) A mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together is
onour Chemistry Unit 3: Quantum Theory, Periodicity and Chemical Bonding Chapter 10: Chemical Bonding II Molecular Geometry & Intermolecular orces 10.1: Molecular Geometry Molecular Structure: - the three-dimensional
Comparing Ionic and Covalent Bonds Chapter 7 Covalent Bonds and Molecular Structure Intermolecular forces (much weaker than bonds) must be broken Ionic bonds must be broken 1 Ionic Bonds Covalent Bonds
Most atoms are not Packet 4: Bonding Atoms will, or share electrons in order to achieve a stable. Octet means that the atom has in its level. If an atom achieves a stable octet it will have the same electron
Answer the following questions. CHEMISTRY BONDING REVIEW 1. What are the three kinds of bonds which can form between atoms? The three types of Bonds are Covalent, Ionic and Metallic. Name Date Block 2.
EXPERIMENT 9 Dot Structures and Geometries of Molecules INTRODUCTION Lewis dot structures are our first tier in drawing molecules and representing bonds between the atoms. The method was first published
Question 4.1: Explain the formation of a chemical bond. A chemical bond is defined as an attractive force that holds the constituents (atoms, ions etc.) together in a chemical species. Various theories
Chapter 8 Concepts of Chemical Bonding Chemical Bonds Three types: Ionic Electrostatic attraction between ions Covalent Sharing of electrons Metallic Metal atoms bonded to several other atoms Ionic Bonding
1. For the following compounds draw the Lewis Structure and determine: (a) The # of Bonding Pairs (b) The # of Lone pairs (c) The electron domain shape (d) The molecular shape (e) Hybridization (f) Whether
Objectives 1. Learn about the structures of covalent compounds and polyatomic ions. 2. Draw Lewis structures based on valence electrons and the octet rule. 3. Construct 3-dimensional models of molecules
BONDING MIDTERM REVIEW 7546-1 - Page 1 1) Which substance contains positive ions immersed in a sea of mobile electrons? A) O2(s) B) Cu(s) C) CuO(s) D) SiO2(s) 2) The bond between hydrogen and oxygen in
CEM110 Week 12 Notes (Chemical Bonding) Page 1 of 8 To help understand molecules (or radicals or ions), VSEPR shapes, and properties (such as polarity and bond length), we will draw the Lewis (or electron
Type of Chemical Bonds Covalent bond Polar Covalent bond Ionic bond Hydrogen bond Metallic bond Van der Waals bonds. Covalent Bonds Covalent bond: bond in which one or more pairs of electrons are shared
Chapter 2 The Chemical Context of Life Multiple-Choice Questions 1) About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living
AP hemistry Practice Test #6 hapter 8 and 9 1. Which of the following statements is incorrect? a. Ionic bonding results from the transfer of electrons from one atom to another. b. Dipole moments result
5. Structure, Geometry, and Polarity of Molecules What you will accomplish in this experiment This experiment will give you an opportunity to draw Lewis structures of covalent compounds, then use those
Chapter 13 - LIQUIDS AND SOLIDS Problems to try at end of chapter: Answers in Appendix I: 1,3,5,7b,9b,15,17,23,25,29,31,33,45,49,51,53,61 13.1 Properties of Liquids 1. Liquids take the shape of their container,
Lewis Dot Notation Ionic Bonds Covalent Bonds Polar Covalent Bonds Lewis Dot Notation Revisited Resonance Lewis Dot notation is a way of describing the outer shell (also called the valence shell) of an
Chapter 10 Molecular Geometry and Chemical Bonding Theory Concept Check 10.1 An atom in a molecule is surrounded by four pairs of electrons, one lone pair and three bonding pairs. Describe how the four
VSEPR Model The structure around a given atom is determined principally by minimizing electron pair repulsions. The Valence-Shell Electron Pair Repulsion Model The valence-shell electron pair repulsion
Vocabulary: VSEPR Valence Shell Electron Pair Repulsion Theory domain = any electron pair, or any double or triple bond is considered one domain. lone pair = non-bonding pair = unshared pair = any electron
APTER SEVEN Molecular Geometry 7.13 Molecular geometry may be defined as the three-dimensional arrangement of atoms in a molecule. The study of molecular geometry is important in that a molecule s geometry
John E. McMurry http://www.cengage.com/chemistry/mcmurry Chapter 2 Polar Covalent Bonds; Acids and Bases Javier E. Horta, M.D., Ph.D. University of Massachusetts Lowell Polar Covalent Bonds: Electronegativity
CHAPTER 10: INTERMOLECULAR FORCES: THE UNIQUENESS OF WATER Problems: 10.2, 10.6,10.15-10.33, 10.35-10.40, 10.56-10.60, 10.101-10.102 10.1 INTERACTIONS BETWEEN IONS Ion-ion Interactions and Lattice Energy
Name: 1) Which molecule is nonpolar and has a symmetrical shape? A) NH3 B) H2O C) HCl D) CH4 7222-1 - Page 1 2) When ammonium chloride crystals are dissolved in water, the temperature of the water decreases.
Bonding in Elements and Compounds Structure of solids, liquids and gases Types of bonding between atoms and molecules Ionic Covalent Metallic Many compounds between metals & nonmetals (salts), e.g. Na,
9.2 Network Covalent, Ionic, and Metallic Solids YOU ARE EXPECTED TO BE ABLE TO: Classify non-molecular solids as either network covalent solids, ionic solids, or metallic solids. Relate the physical properties
Chapter 8 Basic Concepts of the Chemical Bonding 1. There are paired and unpaired electrons in the Lewis symbol for a phosphorus atom. (a). 4, 2 (b). 2, 4 (c). 4, 3 (d). 2, 3 Explanation: Read the question
SME TUGH CLLEGE PRBLEMS! LEWIS DT STRUCTURES 1. An acceptable Lewis dot structure for 2 is (A) (B) (C) 2. Which molecule contains one unshared pair of valence electrons? (A) H 2 (B) H 3 (C) CH 4 acl 3.
AS Chemistry Revision Notes Unit Atomic Structure, Bonding And Periodicity Atomic Structure. All atoms have a mass number, A (the number of nucleons), and a proton number, Z (the number of protons). 2.
Sample Exercise 8.1 Magnitudes of Lattice Energies Without consulting Table 8.2, arrange the ionic compounds NaF, CsI, and CaO in order of increasing lattice energy. Analyze From the formulas for three
BOND TYPES: THE CLASSIFICATION OF SUBSTANCES Every (pure) substance has a unique set of intrinsic properties which distinguishes it from all other substances. What inferences, if any can be made from a
Chem 1: Chapter 10 Page 1 Chapter 10 Molecular Geometry and Chemical Bonding Theory I) VSEPR Model Valence-Shell Electron-Pair Repulsion Model A) Model predicts Predicts electron arrangement and molecular
Name: Exam 2 Chemistry 65 Summer 2015 Score: Instructions: Clearly circle the one best answer 1. Valence electrons are electrons located A) in the outermost energy level of an atom. B) in the nucleus of
hemistry for Biomedical Engineering. Exercises Topic 2 Authors: ors: Juan Baselga & María González Exercises Topic 2: Molecules 1. Using hybridization concepts and VSEPR model describe the molecular geometry
S block elements p block elements and chemical bonding -1 1.Group I elements do not occur free (native state) in the nature because a. They are unstable b. Their compounds with other elements are highly
Chemistry B2A Chapter 12 Chemical Bonding Octet rule-duet role: when undergoing chemical reaction, atoms of group 1A-7A elements tend to gain, lose, or share sufficient electrons to achieve an electron
hemistry 121 Problem set V olutions - 1 hem 121 Problem et V Lewis tructures, VEPR and Polarity AWER 1. pecies Elecronegativity difference in bond Bond Polarity Mp 3 E = 3.0-3.0 = 0 for - very weakly polar
Sample Exercise 8.1 Magnitudes of Lattice Energies Without consulting Table 8.2, arrange the following ionic compounds in order of increasing lattice energy: NaF, CsI, and CaO. Analyze: From the formulas
Basic Chemistry Why do we study chemistry in a biology course? All living organisms are composed of chemicals. To understand life, we must understand the structure, function, and properties of the chemicals
NAME 1. When compared to H 2 S, H 2 O has a higher 8. Given the Lewis electron-dot diagram: boiling point because H 2 O contains stronger metallic bonds covalent bonds ionic bonds hydrogen bonds 2. Which
SCH4U UNIT TEST Atomic & Molecular Structure Name: _ Date: Part A - Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. Who postulated that electrons
CHEMISTRY 1710 - Practice Exam #5 - SPRING 2014 (KATZ) Name: Score: This is a multiple choice exam. Choose the BEST answer from the choices which are given and write the letter for your choice in the space
Science of Kriyayoga IST 111-01, Spring 2005 Matter, Elements, Compounds, Chemical Bonds and Energy In our discussion so far, we have discussed human nervous system and cell biology, in addition to the
Chem 1A Dr. White Updated /5/1 1 Chemistry Workbook 2: Problems For Exam 2 Section 2-1: Covalent Bonding 1. On a potential energy diagram, the most stable state has the highest/lowest potential energy.
Ch. 8 Vocabulary 2 Covalent Bonding Chapter 8 Covalent bond Molecule Lewis Structure Sigma bond Pi bond Bond Dissociation Energy Endothermic Reaction Exothermic Reaction Structural Formula (Ch. 8.3) Polar
Chapter 10 Bonding: Lewis electron dot structures and more Bonding is the essence of chemistry! Not just physics! Chemical bonds are the forces that hold atoms together in molecules, in ionic compounds,
Bond strength IMF strength Oct 6 10:43 AM Oct 14 10:06 PM 1 Oct 14 10:07 PM Oct 14 10:07 PM 2 Oct 14 10:10 PM Oct 14 10:11 PM 3 comparing ionic and covalent bonding.notebook October 16, 2014 Hardness Ionic
Unit C Practice Problems Chapter 8 1. Draw the lewis structures for the following molecules: a. BeF 2 b. SO 3 c. CNS 1- d. NO 2. The correct Lewis symbol for ground state carbon is a) b) c) d) e) 3. Which
Bonds hapter 8 Bonding: General oncepts Forces that hold groups of atoms together and make them function as a unit. Bond Energy Bond Length It is the energy required to break a bond. The distance where
Ionic and Covalent Bonds Ionic Bonds Transfer of Electrons When metals bond with nonmetals, electrons are from the metal to the nonmetal The becomes a cation and the becomes an anion. The between the cation
INTERMOLECULAR FORCES Intermolecular forces- forces of attraction and repulsion between molecules that hold molecules, ions, and atoms together. Intramolecular - forces of chemical bonds within a molecule
1. Each element has its own characteristic atom in which a. the atomic mass is constant. b. the atomic number is constant. c. the mass number is constant. d. two of the above are correct. e. all of the
Questions on Chapter 8 Basic Concepts of Chemical Bonding Circle the Correct Answer: 1) Which ion below has a noble gas electron configuration? A) Li 2+ B) Be 2+ C) B2+ D) C2+ E) N 2-2) Of the ions below,
ATER 10 TE AE MLEULE EMIAL ETI BED READIG RBLEM B10.1 lan: Examine the Lewis structure, noting the number of regions of electron density around the carbon and nitrogen atoms in the two resonance structures.
TRENDS IN ATOMIC PROPERTIES: THE PERIODIC TABLE Electron configurations determine organization of the periodic table Next properties of elements and their periodic behavior Elemental properties determined
CHAPTER 1 2 Ionic Bonds SECTION Chemical Bonding BEFORE YOU READ After you read this section, you should be able to answer these questions: What is ionic bonding? What happens to atoms that gain or lose
Electronic Structure and the Periodic Table Learning Outcomes (a) Electronic structure (i) Electromagnetic spectrum and associated calculations Electromagnetic radiation may be described in terms of waves.
(Revised 05/22/2015) Introduction In the early 1900s, the chemist G. N. Lewis proposed that bonds between atoms consist of two electrons apiece and that most atoms are able to accommodate eight electrons
Chapter 2: Chemical Compounds and Bonding Section 2.1: Ionic Compounds, pages 22 23 1. An ionic compound combines a metal and a non-metal joined together by an ionic bond. 2. An electrostatic force holds
Unit 2 Periodic Behavior and Ionic Bonding 6.1 Organizing the Elements I. The Periodic Law A. The physical and chemical properties of the elements are periodic functions of their atomic numbers B. Elements
1 SAPES MLEULES (VSEPR MDEL) Valence Shell Electron-Pair Repulsion model - Electron pairs surrounding atom spread out as to minimize repulsion. - Electron pairs can be bonding pairs (including multiple
Chapter 9 Molecular Geometry & Bonding Theories I) Molecular Geometry (Shapes) Chemical reactivity of molecules depends on the nature of the bonds between the atoms as well on its 3D structure Molecular
Structures and Properties of Substances Introducing Valence-Shell Electron- Pair Repulsion (VSEPR) Theory The VSEPR theory In 1957, the chemist Ronald Gillespie and Ronald Nyholm, developed a model for
Chapter 18: How Atoms Bond and Molecules Attract Name: 18.1: Electron-Dot Structures Help Us to Understand Bonding What are the 3 types of bonds we will be learning about? When 2 atoms meet, which part
2. VALENT BNDING, TET RULE, PLARITY, AND BASI TYPES F FRMULAS LEARNING BJETIVES To introduce the basic principles of covalent bonding, different types of molecular representations, bond polarity and its
TYPES EMIAL BDIG 1 Ionic Bonding - Bond between ions whose charges attract each other - ne atom gives electrons and one atom takes electrons. Example a + l - ionic bond ovalent Bonding - two atoms each
129 Lewis Structures G. N. Lewis hypothesized that electron pair bonds between unlike elements in the second (and sometimes the third) row occurred in a way that electrons were shared such that each element
hemistry 15, hapter 7 Exercises Types of Bonds 1. Using the periodic table classify the bonds in the following compounds as ionic or covalent. If covalent, classify the bond as polar or not. Mg2 4 i2 a(3)2
APTER 8 hemical Bonding Atoms of elements (except Gp.8A) exist in some form of aggregation. All compounds made (by chemical combination) of different elements exist in some form of aggregation of elements.
7.4 Using the Bohr Theory LEARNING TIP Models such as Figures 1 to 4, on pages 218 and 219, help you visualize scientific explanations. As you examine Figures 1 to 4, look back and forth between the diagrams
Name: Class: Date: ID: A Chapter 6 Assessment Multiple Choice Identify the choice that best completes the statement or answers the question. 1. When an atom loses an electron, it forms a(n) a. anion. c.
4 Bonding We learned in Chapter 2 that all elements are made of atoms and that there are only about 100 chemically different types of atom. Yet we know that we live in a world made up of literally millions
1 Chapter 10 Liquids & Solids * 10.1 Polar Covalent Bonds & Dipole Moments - van der Waals constant for water (a = 5.28 L 2 atm/mol 2 ) vs O 2 (a = 1.36 L 2 atm/mol 2 ) -- water is polar (draw diagram)
Bonding Models Section (Chapter, M&T) Chemical Bonding We will look at three models of bonding: Lewis model Valence Bond model M theory Bonding Models (Lewis) Bonding Models (Lewis) Lewis model of bonding