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Introduction to Bonding

Learn about the different types of chemical bonds including covalent, ionic, and metallic bonds. Understand bond formation, bond polarity, and how to draw Lewis structures. Practice drawing dot structures for various covalent compounds.

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Introduction to Bonding

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  1. Chemical Bonding Introduction toBonding

  2. A. Vocabulary • Chemical Bond • attractive force between atoms or ions that binds them together as a unit

  3. B. Types of Bonds COVALENT IONIC e- are transferred from metal to nonmetal e- are shared between two nonmetals Bond Formation Type of Structure true molecules crystal lattice Physical State liquid or gas solid Melting Point low high Solubility in Water yes usually not yes (solution or liquid) Electrical Conductivity no Other Properties odorous

  4. B. Types of Bonds METALLIC e- are delocalized among metal atoms Bond Formation Type of Structure “electron sea” Physical State solid Melting Point very high Solubility in Water no yes (any form) Electrical Conductivity malleable, ductile, lustrous Other Properties

  5. B. Types of Bonds Ionic Bonding - Crystal Lattice • Remember: Opposites Attract! RETURN

  6. B. Types of Bonds Metallic Bonding - “Electron Sea” RETURN

  7. B. Types of Bonds Covalent Bonding - True Molecules Diatomic Molecule RETURN

  8. C. Bond Polarity • Nonpolar Covalent Bond • e- are shared equally • usually between identical atoms • Ex. F2

  9. - + C. Bond Polarity • Polar Covalent Bond • e- are shared unequally • results in partial charges (dipole)

  10. C. Bond Polarity • Polar Covalent Bond • more electronegative atom has a partial negative charge  - • less electronegative atom has a partial positive charge +

  11. C. Bond Polarity • Difference in electronegativity determines bond type. • Above 1.7 = ionic • 0.3-1.7 = polar covalent • 0- up to 0.3 = non-polar covalent

  12. C. Bond Polarity Examples: • Cl2 • HCl • NaCl 3.0-3.0=0.0 Nonpolar 3.0-2.1=0.9 Polar 3.0-0.9=2.1 Ionic

  13. C. Bond Polarity • Nonpolar • Polar • Ionic View Bonding Animations.

  14. X 2s 2p D. Lewis Structures • Electron Dot Diagrams • show valence e- as dots • EX: oxygen O

  15. D. Lewis Structures • Covalent – show sharing of e- • Ionic – show transfer of e-

  16. D. Lewis Structures Ionic – show transfer of e-

  17. Practice • Draw Dot Structures for the IONIC COMPOUNDS that form between the following elements • Sodium and Sulfur • Beryllium and Bromine

  18. - + + D. Lewis Structures • Nonpolar Covalent - no charges • Polar Covalent - partial charges

  19. Steps for Building a Dot Structure for Covalent Compounds Ammonia, NH3 1. Decide on the central atom; never H. Why? Most of the time, this is the least electronegative atom Therefore, N is central on this one 2. Add up the number of valence electrons that can be used. H = 1 and N = 5 Total = (3 x 1) + 5 = 8 electrons NH3

  20. H H H H N N H H Building a Dot Structure 3. Form a single bond between the central atom and each surrounding atom (each bond takes 2 electrons!) 4. Remaining electrons form LONE PAIRS to complete the octet •• 3 BONDING PAIRS and 1 LONE PAIR.

  21. H H N H • Check to make sure there are 8 electrons around each atom except H. • H should only have 2 electrons. 6. Also, check the number of electrons in your drawing with the number of electrons from step 2. • If you have more electrons in the drawing than in step 2, you must make double or triple bonds. ••

  22. Carbon Dioxide, CO2 1. Central atom = 2. Valence electrons = 3. Form bonds. C 4 e-O 6 e- X 2 O’s = 12 e-Total: 16 valence electrons This leaves 12 electrons (6 pair). 4. Place lone pairs on outer atoms. 5. Check to see that all atoms have 8 electrons around it except for H, which can have 2.

  23. Carbon Dioxide, CO2 C 4 e-O 6 e- X 2 O’s = 12 e-Total: 16 valence electrons How many are in the drawing? 6. There are too many electrons in our drawing. We must form DOUBLE BONDS between C and O. Instead of sharing only 1 pair, a double bond shares 2 pairs. So one pair is taken away from each atom and replaced with another bond.

  24. H2CO Double and even triple bonds are commonly observed for C, N, P, O, and S SO3 C2F4

  25. Practice • Draw the Dot Structure of the following COVALENT COMPOUNDS • CCl4 • SO2 • SO42-

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