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Ch 6 Covalent Bonding

Ch 6 Covalent Bonding. Think about differences between ionic & covalent bonding. Ch 6 Covalent Bonding. Chemical bond, p. 160: attraction between nuclei and valence e - of different atoms. bonds form in order to decrease potential energy (PE) increase stability.

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Ch 6 Covalent Bonding

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  1. Ch 6 Covalent Bonding Think about differences between ionic & covalent bonding

  2. Ch 6 Covalent Bonding Chemical bond, p. 160: attraction between nuclei and valence e- of different atoms. bonds form in order to decrease potential energy (PE) increase stability

  3. 1. Covalent bonding, p. 161: sharing of e- pairs between two atoms. O=O O2

  4. Examples: HCl O2 CO2 Covalent bonding: always between NONMETAL – NONMETAL!

  5. 2. Nonpolar Covalent Bond, p. 162 • e- are shared equally • symmetrical e- density • usually identical atoms Ex: Cl2 , O2 Ref: NISD

  6. - + 3. Polar Covalent Bond, p. 162 • e- are shared unequally • asymmetrical e- density • results in partial charges (dipole) Ref: NISD

  7. 4. Polar/polarity, p. 162 • Most bonds are a blend of ionic and covalent characteristics. • Difference in electronegativity determines bond type. Ref: NISD

  8. 4. Polar/polarity, p. 162 • Polar bonds have uneven distribution of charge because e- are shared unequally.

  9. 5. Electronegativity, p. 151 • Attraction an atom has for a shared pair of electrons. • higher e-neg atom  - • lower e-neg atom + Ref: NISD

  10. 5. Electronegativity Trend: ability of element to attract e- • Increases up and to the right. • Nonmetals have  electroneg (want e-) Ref: NISD

  11. 5. Electronegativity: the difference determines bond type

  12. 5. Electronegativity • Example: What type of bond will H and Cl form? • Look up e-neg (p. 151) and take difference (subtract).

  13. 5. Electronegativity Example: What type of bond will H and Cl form? H = 2.1 Cl = 3.0

  14. 5. Electronegativity Example: What type of bond will H and Cl form? H = 2.1 Cl = 3.0 D = 0.9

  15. 5. Electronegativity Example: What type of bond will H and Cl form? H = 2.1 Cl = 3.0 D = 0.9 HCl forms a polar covalent bond.

  16. 7. Molecular compound/formula, p. 164:   shows types and # atoms combined in single molecule. Example: HCl NH3

  17. Diatomic molecule, p. 164: contains only two (2) atoms. Ex: Cl2 F2 O2

  18. H N O F Cl Br I 8. Diatomic molecule: seven ‘same atom’ diatomics; form a 7 on periodic table.

  19. 9. Metallic bond: p. 181 attraction between metal atoms and “sea of e-”; e- are mobile; malleable NISD

  20. 9. Metallic bond: p. 181 attraction between metal atoms and “sea of e-”; e- are mobile

  21. 10. Lewis Structure: show arrangement of valence e-.

  22. Unshared pairs 11. Lone pair e- , p. 171: unshared pair of e- ; not involved in bonding

  23. Shared pair 12. Shared pair e-:  e- involved in bonding

  24. Shared pair Two shared pairs Single bond: one pair e- shared. F2 13. Double bond: two pairs e- shared. O2

  25. 3 shared pairs 14. Triple bond: three (3) pairs e- shared. Ex. N2

  26. Share valence e- Weaker bond Molecules Soft, gas Less soluble in H2O Poor/partial conductors Ex. CO2 Lose/gain valence e- Stronger bond Crystals/formula unit Hard, brittle Soluble in H2O Good conductors Ex. NaCl Covalent vs. Ionic Bonds

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