The Nature of Covalent Bonding Covalent Bonds The

The Nature of Covalent Bonding > Covalent Bonds The Nature of Covalent Bonds 10/23/2015 Page 217 Slide 1 of 50 © Copyright Pearson Prentice Hall End Show

The Nature of Covalent Bonding > In our last lecture we learned to 8. 1. 1 Distinguish between the melting points and boiling points of molecular compounds and ionic compounds. 8. 1. 2 Describe the information provided by a molecular formula. Slide 2 of 50 © Copyright Pearson Prentice Hall End Show

The Nature of Covalent Bonding > Georgia Professional Standards SC 3 Students will use the modern atomic theory to explain the characteristics of atoms. e. Compare and contrast types of chemical bonds (i. e. ionic, covalent). Slide 3 of 50 © Copyright Pearson Prentice Hall End Show

The Nature of Covalent Bonding > After tomorrows lecture the student shall be able to: 8. 2. 1 Describe how electrons are shared to form covalent bonds and identify exceptions to the octet rule. 8. 2. 2 Demonstrate how electron dot structures represent shared electrons. 8. 2. 3 Describe how atoms form double or triple covalent bonds. 8. 2. 4 Distinguish between a covalent bond a coordinate covalent bond and describe how the strength of a covalent bond is related to its bond dissociation energy. 8. 2. 5 Describe how oxygen atoms are bonded in ozone. Slide 4 of 50 © Copyright Pearson Prentice Hall End Show

The Nature of Covalent Bonding > Vocabulary Words single covalent bond, structural formula, unshared pair, double covalent bond, triple covalent bond, coordinate covalent bond, polyatomic ion, bond dissociation energy, resonance structure Slide 5 of 50 © Copyright Pearson Prentice Hall End Show

8. 2 The Nature of Covalent Bonding > The Octet Rule in Covalent Bonding What is the result of electron sharing in covalent bonds? Slide 6 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > The Octet Rule in Covalent Bonding In covalent bonds, electron sharing usually occurs so that atoms attain the electron configurations of noble gases. Slide 7 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Single Covalent Bonds How do electron dot structures represent shared electrons? Slide 8 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Single Covalent Bonds Two atoms held together by sharing a pair of electrons are joined by a single covalent bond. Slide 9 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Single Covalent Bonds An electron dot structure such as H: H represents the shared pair of electrons of the covalent bond by two dots. A structural formula represents the covalent bonds by dashes and shows the arrangement of covalently bonded atoms. Slide 10 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Single Covalent Bonds The halogens form single covalent bonds in their diatomic molecules. Fluorine is one example. Slide 11 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Single Covalent Bonds A pair of valence electrons that is not shared between atoms is called an unshared pair, also known as a lone pair or a nonbonding pair. Slide 12 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Single Covalent Bonds The hydrogen and oxygen atoms attain noblegas configurations by sharing electrons. Slide 13 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Single Covalent Bonds The ammonia molecule has one unshared pair of electrons. Slide 14 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Single Covalent Bonds Methane has no unshared pairs of electrons. Slide 15 of 50 © Copyright Pearson Prentice Hall

8. 1 Section Assessment Slide 16 of 50 © Copyright Pearson Prentice Hall

Section Assessment Slide 17 of 50 © Copyright Pearson Prentice Hall

8. 1 Section Assessment Slide 18 of 50 © Copyright Pearson Prentice Hall

Practice Problems for Conceptual Problem 8. 1 Section Assessment Problem Solving 8. 8 Solve Problem 8 with the help of an interactive guided tutorial. Slide 19 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Double and Triple Covalent Bonds How do atoms form double or triple covalent bonds? Slide 20 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Double and Triple Covalent Bonds Atoms form double or triple covalent bonds if they can attain a noble gas structure by sharing two pairs or three pairs of electrons. Slide 21 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Double and Triple Covalent Bonds A bond that involves two shared pairs of electrons is a double covalent bond. A bond formed by sharing three pairs of electrons is a triple covalent bond. Slide 22 of 50 © Copyright Pearson Prentice Hall

The Nature of Covalent Bonding > Covalent Bonds Simulation 6 Simulate the covalent bonding between molecules Slide 23 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Double and Triple Covalent Bonds Each nitrogen atom has one unshared pair of electrons. Slide 24 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Double and Triple Covalent Bonds Slide 25 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Double and Triple Covalent Bonds Carbon dioxide gas is soluble in water and is used to carbonate many beverages. A carbon dioxide molecule has two carbon-oxygen double bonds. Slide 26 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Double and Triple Covalent Bonds Carbon dioxide is an example of a triatomic molecule. Slide 27 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Coordinate Covalent Bonds How are coordinate covalent bonds different from other covalent bonds? Slide 28 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Coordinate Covalent Bonds In carbon monoxide, oxygen has a stable configuration but the carbon does not. Slide 29 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Coordinate Covalent Bonds As shown below, the dilemma is solved if the oxygen donates one of its unshared pairs of electrons for bonding. Slide 30 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Coordinate Covalent Bonds A coordinate covalent bond is a covalent bond in which one atom contributes both bonding electrons. In a structural formula, you can show coordinate covalent bonds as arrows that point from the atom donating the pair of electrons to the atom receiving them. Slide 31 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Coordinate Covalent Bonds In a coordinate covalent bond, the shared electron pair comes from one of the bonding atoms. Slide 32 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Coordinate Covalent Bonds A polyatomic ion, such as NH 4+, is a tightly bound group of atoms that has a positive or negative charge and behaves as a unit. Most plants need nitrogen that is already combined in a compound to grow. Slide 33 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Coordinate Covalent Bonds Slide 34 of 50 © Copyright Pearson Prentice Hall

8. 2 Section Assessment Slide 35 of 50 © Copyright Pearson Prentice Hall

8. 2 Section Assessment Slide 36 of 50 © Copyright Pearson Prentice Hall

8. 2 Section Assessment Slide 37 of 50 © Copyright Pearson Prentice Hall

Practice Problems for Conceptual Problem 8. 2 Section Assessment Problem-Solving 8. 10 Solve Problem 10 with the help of an interactive guided tutorial. Slide 38 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Bond Dissociation Energies How is the strength of a covalent bond related to its bond dissociation energy? Slide 39 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Bond Dissociation Energies The energy required to break the bond between two covalently bonded atoms is known as the bond dissociation energy. A large bond dissociation energy corresponds to a strong covalent bond. Slide 40 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Resonance How are oxygen atoms bonded in ozone? Slide 41 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Resonance Ozone in the upper atmosphere blocks harmful ultraviolet radiation from the sun. At lower elevations, it contributes to smog. Slide 42 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Resonance The actual bonding of oxygen atoms in ozone is a hybrid, or mixture, of the extremes represented by the resonance forms. Slide 43 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Resonance A resonance structure is a structure that occurs when it is possible to draw two or more valid electron dot structures that have the same number of electron pairs for a molecule or ion. Slide 44 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Exceptions to the Octet Rule What are some exceptions to the rule? Slide 45 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Exceptions to the Octet Rule The octet rule cannot be satisfied in molecules whose total number of valence electrons is an odd number. There also molecules in which an atom has fewer, or more, than a complete octet of valence electrons. Slide 46 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Exceptions to the Octet Rule Two electron dot structures can be drawn for the NO 2 molecule. Slide 47 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Exceptions to the Octet Rule NO 2 is produced naturally by lightning strikes. Slide 48 of 50 © Copyright Pearson Prentice Hall

8. 2 The Nature of Covalent Bonding > Exceptions to the Octet Rule The electron dot structure for PCl 5 can be written so that phosphorus has ten valence electrons. Slide 49 of 50 © Copyright Pearson Prentice Hall

8. 2 Section Quiz. Assess students’ understanding of the concepts in Section 8. 2. Continue to: -or- Launch: Section Quiz Slide 50 of 50 © Copyright Pearson Prentice Hall

8. 2 Section Quiz. 1. In covalent bonding, atoms attain the configuration of noble gases by a. losing electrons. b. gaining electrons. c. transferring electrons. d. sharing electrons. Slide 51 of 50 © Copyright Pearson Prentice Hall

8. 2 Section Quiz 2. Electron dot diagrams are superior to molecular formulas in that they a. show which electrons are shared. b. indicate the number of each kind of atom in the molecule. c. show the arrangement of atoms in the molecule. d. are easier to write or draw. Slide 52 of 50 © Copyright Pearson Prentice Hall

8. 2 Section Quiz 3. Which of the following molecules would contain a bond formed when atoms share three pairs of electrons? a. Se 2 b. As 2 c. Br 2 d. Te 2 Slide 53 of 50 © Copyright Pearson Prentice Hall

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