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Ch. 8 – Covalent Compounds I. Bond Polarity and IMF (237 – 241)

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Presentation on theme: "Ch. 8 – Covalent Compounds I. Bond Polarity and IMF (237 – 241)"— Presentation transcript:

1 Ch. 8 – Covalent Compounds I. Bond Polarity and IMF (237 – 241)

2 A. Bond Polarity Most bonds are a blend of ionic and covalent characteristics Difference in electronegativity determines bond type

3 A. Bond Polarity Electronegativity Attraction an atom has for a shared pair of electrons higher e - neg atom - lower e - neg atom + Draw the Lewis structure for HCl & label partial charges

4 A. Bond Polarity Electronegativity Trend (p. 178) Increases up and to the right

5 Nonpolar Covalent Bond e - are shared equally symmetrical e - density usually identical atoms A. Bond Polarity

6 + - Polar Covalent Bond e - are shared unequally asymmetrical e - density results in partial charges (dipole)

7 A. Bond Polarity Determine bond polarity: C – O Ca – O Si – Cl H – F N – N 3.44 – 2.55 = 0.89 3.44 – 1.00 = 2.44 3.16 – 1.90 = 1.26 3.98 – 2.20 = 1.78 3.04 – 3.04 = 0.00 PC Ionic PC Ionic NPC

8 Nonpolar Polar Ionic View Bonding Animations.Bonding Animations A. Bond Polarity

9 B. Molecular Polarity Polar molecule = one end slightly + and one end slightly – Molecule with 2 poles = dipolar molecule or dipole

10 B. Molecular Polarity Shape, symmetry and bond polarity determines molecular polarity H – O bond is polar and water is asymmetrical, so H 2 O is polar C – Cl bond is polar, but CCl 4 is symmetrical, so molecule is nonpolar

11 B. Molecular Polarity Identify each molecule as polar or nonpolar SCl 2 O 2 CS 2 CF 4 CH 2 F 2 Tetrahedral, bent polar Nonpolar bonds nonpolar Linear nonpolar Tetrahedral nonpolar Tetrahedral polar

12 C. Definition of IMF IMF = Intermolecular Forces Attractive forces between molecules Much weaker than chemical bonds within molecules

13 D. Types of IMF Van der Waals

14 D. Types of IMF London Dispersion Forces View animation online.animation

15 D. Types of IMF Dipole-Dipole Forces + - View animation online.animation

16 D. Types of IMF Hydrogen Bonding

17 PCl 3 polar = dispersion, dipole-dipole CH 4 nonpolar = dispersion HF H-F bond = dispersion, dipole- dipole, hydrogen bonding E. Determining IMF

18 Substances in which all atoms are covalently bonded to each other Very stable Examples Diamonds – Carbon covalently bonded to carbonDiamonds Quartz – SiO 2 covalently bonded and not distinct molecules F. Network SolidsNetwork Solids F. Network SolidsNetwork Solids

19 II. Ions (p. 194 – 200) Ch. 7 – Ionic Bonds & Properties

20 The lowest whole-number ratio of ions in an ionic compound A. Formula Unit

21 Oppositely charged ions attract, force that holds them together = ionic bond Electrons are transferred from cations to anions Bonds formed between metals and nonmetals (or contain a polyatomic ion) B. Ionic Bonds

22 Most ionic compounds are crystalline solids at room temp Ionic compounds generally have high melting points Large attractive forces result in very stable structures B. Properties of Ionic Compounds

23 III. Bonding in Metals (p. 201 – 203) Ch. 7 – Ionic and Metallic Bonding

24 A. Metallic Character Metals Nonmetals Metalloids

25 good conductors because the valence electrons are able to flow freely Valence electrons of metals can be thought of as a sea of electrons Properties can be explained by the mobility of electrons in metals B. Metals

26 Metallic Bonding - Electron Sea C. Metallic Bond

27 Properties can be explained by the mobility of electrons in metals When subjected to pressure, the cations easily slide past each other like a ball bearing immersed in oil D. Metallic Properties

28 electron sea METALLIC Bond Formation Smallest Unit Melting Point E. Summary Physical State @ RT e - are delocalized among metal atoms very high solid

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