1 / 58

Covalent Bonding

Covalent Bonding. Chapter 9. Now, let’s talk about SHARING electrons. Or, a COVALENT BOND!. 1. Covalent Bonding. Cmpd formed called molecule ; Ex: C 12 H 22 O 11 CO 2 share valence electrons Usually elements that are close together Usually 2 NM.

nam
Télécharger la présentation

Covalent Bonding

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Covalent Bonding Chapter 9

  2. Now, let’s talk about SHARING electrons. Or, a COVALENT BOND!

  3. 1. Covalent Bonding • Cmpd formed called molecule; • Ex: C 12 H 22 O 11 CO 2 • share valence electrons • Usually elements that are closetogether • Usually 2 NM

  4. Biology Connection • Most covalent bonds are: Macro moleculesPurposeElem 1. 2. 3. 4. All elements have _______ in common.

  5. 2. How to Form C-B • Ex: H 2 Drawn: • e- dot for each (also called _________) • Draw circles around each elem (at the top) to share valence electrons

  6. Try: • NH 3 ammonia • Also called _______________ • Draw e- dot for each element (use white board first) • Draw as a structural formula go

  7. .. H-N- H H Lone Pairs go

  8. Lone Pairs • Unshared electrons • What could they potentially do? • Bond w/ another element go

  9. Covalent Bonds Sharing electrons to fill the outer most shells of both the hydrogen atoms and the oxygen atom = now everyone is “happy”. go

  10. Covalent Bonds go

  11. Nonpolar Covalent Bonds: Dogs of equal strength (equal sharing!)

  12. Diatomic Elements Beside part #2 • Ex (name all 7):

  13. 7 rule There is 1 extra on here

  14. Could be: • Single bond C-C (easier to break) • Double bond C=C • Triple bond C= C (harder to break) (single bond prod elem far apart, double is closer, etc. The “longer the bond length gives it strength”) go

  15. go

  16. Double and Triple bonds • Helps economizee- • Cmpd won’t bond with as many dif atoms • ADD: The energy to break a covalent bond is called Bond Dissociation Energy

  17. Organic Cmpds • Organic compounds • Means natural, living, C-based

  18. 3. Dashes or Dots? -------- represent valence e- in a bond; 1 pr (2 e-) .. Represent unshared electrons End of pg 1

  19. 4. Three 3 Exceptions to Octet • < 8 val e-  Be Sn B Ex: BF3

  20. > 8 val e-  P As S -Noble gas config? s2p6 -where do extra e- stay? 3 d Ex: SF4

  21. Odd total # of electrons -usually N -ex: NO No octet? No Is it stable? No

  22. 5. Properties • Low MP & BP • No ions  neutral b/c they share e- • Electrolyte? No • Crystal lattice weak  called covalent network • Phases: mostly S some L

  23. 6. Drawing structural formulas/Lewis Structures AB 2 E 2 A is central atom -usually least electronegative (carbon always central) (electroneg on the left) Hydrogen is never central element -lowest # of atoms

  24. AB 2 E 2 B is terminal atom (side) -usually mentioned 2nd -more eleneg; on right -bigger # of atoms

  25. AB 2 E 2 E called lone e- or lone prs go on central atom

  26. A little advice on Lewis Structures: 1. Form bonds between atoms (2 e-). 2. Distribute remaining e- to give each atom an octet (recall exceptions). 3. If there aren’t enough e- to go around, form double or triple bonds. examples

  27. NH3 • ammonia • N: 5 x 1 = 5 val e- • H: 1 x 3 = 3 total val e- • total = 8 total val e- for both N & H • N is central

  28. N2 • nitrogen gas • N: 5 val e- x 2 N’s = • 10 total electrons

  29. Those on your paper: 1. 2. 3. 4. 5.

  30. 6. 7. 8. 9.

  31. NH4+ : ammonium ion

  32. SO42- : sulfate ion • 5 x 6 = 30 • total = 30 + 2 = 32 OH- : hydroxide ion • 6 + 1 + 1 = 8 total

  33. Those on your paper: 10. 11. 12. 13.

  34. Resonance Structures • ADD-resonance – bonding between atoms that cannot be represented on Lewis structure • (It shows all possible structures) End of page 2

  35. Electronegativity Chart

  36. Electronegativity & Polarity • Recall e- affinity: • Electronegativity: ability to attract e- • Helpful to determine bond type • How? Take difference b/w elements Use eleneg chart; F= _____; what is least eleneg?______ PT

  37. Covalent can be: • Polar • e- pulled: • Oppositely charged: • Stronger e- attraction: • Usually 2 ______ elements • Use “partial charge” symbol to show + & - charges as e- are pulled to one atom

  38. Ex: H – Cl Written: or Also called:Dipole-Dipole -attraction b/w opposite charged atoms on polar mole. go

  39. go

  40. Nonpolar • Atoms in bond pull: • Usually 2 of the ________ element • Ex:

  41. Nonpolar Covalent bonds– electrons are being shared EQUALLY!! Oxygen Atom Oxygen Atom Oxygen Molecule (O2)

  42. Electronegativity Scale • Used as a guide 0 4 Try samples at the bottom of the page using the chart on the next slide.

  43. Ex: Electronegativity Chart

  44. **Covalent bonds are usually _____________ b/w 2 dif elem **__________ w/ individual elem; Ionic is ___________

  45. Polarity and Solubility • Polar and Ionic usually solbule in polar substances • Rule: “Like dissolves like” Physical property

  46. Intermolecular Forces Also called van der Waals forces • Covalent • Vary in strength • Weaker than ionic • 3 types

  47. They lead to prop of covalent bonds: • ______ MP & BP • Exist as ______/or vaporize easily • _______ solids (like paraffin wax, pencil)

More Related