1 / 40

Catalyst

Catalyst. 1. Draw the Lewis Structure for BCl 3 . 2. Draw the Lewis Structure for HCN. 3. Draw the Lewis Structure for PCl 5. Formal Charges. Many compounds have more than 1 possible Lewis structure. Formal charges tells us the “right” Lewis structure.

akaiser
Download Presentation

Catalyst

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. Catalyst 1. Draw the Lewis Structure for BCl3. 2. Draw the Lewis Structure for HCN. 3. Draw the Lewis Structure for PCl5

  2. Formal Charges • Many compounds have more than 1 possible Lewis structure. • Formal charges tells us the “right” Lewis structure. • Formal Charge – The charge an element would have if all electrons were shared equally. • The “best” structure has: 1. Atoms that have formal charges closest to 0 2. Highest negative charge on the most electronegative atom

  3. Calculating Formal Charges • To calculate formal charge:

  4. Class Example • Draw NCS–, calculate its formal charge and pick the “best” Lewis structure.

  5. Table Talk • Draw the Lewis structure for PF3 and label the formal charge of all atoms

  6. Meet the Bicarbonate Ion…

  7. HCO3 – + H+ H2CO3  CO2 + H2O

  8. Justify – TPS • Which structure of bicarbonate drawn on the board is “right” according to our rules of formal charges?

  9. Lecture 2.2 – Resonance Structures and Polar Covalent Compounds

  10. Today’s Learning Target • LT 2.4 – I can discuss the reason for the formation of resonance Lewis Structures and I can draw resonance structures for a variety of covalent compounds.

  11. Resonance Structures • Oftentimes, there is more than one “correct” way to draw a Lewis structure. • This occurs because there are multiple drawings with the same formal charges.

  12. Class Example • Draw all the allowed structures for O3

  13. Resonance Structures • For O3, both structures are equally valid • Resonance Structures – Molecules that require multiple Lewis Structures to describe the distribution of electrons. • Both structures are present in equal amounts

  14. Resonance Structure for Ozone

  15. Table Talk • Draw all the correct structures for SO3-

  16. Table Talk • Draw all correct resonance structures for HCO2-

  17. Coach and Correct

  18. Question 1 • Draw all resonance structures for the nitrate ion

  19. Question 2 • Draw all resonance structures for the phosphate ion

  20. Question 3 • Draw all resonance structures for S2CO-2

  21. Question 4 • Draw all resonance structures for SCN -

  22. Question 5 • Draw all resonance structures for CHO2-

  23. Amazing Bending Water!

  24. Justify – TPS • What caused the water to bend?

  25. Today’s Learning Targets • LT 2.5 – I can characterize ionic and covalent compounds utilizing the idea of electronegativity. Furthermore, I can discuss how electronegativity differences lead to the formation of polar covalent bonds

  26. Electronegativity • Electronegativity – The ability of an atom in a molecule to attraction electrons to itself. • Increases as you move across a period • Adding more protons, but not adding more energy levels • Decreases as you go down a group • Adding more energy levels makes it harder for the nucleus to attract new electrons

  27. Covalent Bond Polarity • Oftentimes, when atoms are in a covalent bond, electrons are not shared equally. • Nonpolar Covalent Bond – Electrons shared equally between the atoms • Polar Covalent Bond – Electrons shared unequally due to difference in electronegativity • Electrons in a covalent bond reside closest to the atom that is most electronegative

  28. F H Because fluorine is drastically more electronegative, it holds electrons closer to itself when in a covalent bond with hydrogen.

  29. F H Hydrogen is given a partial positive charge and fluorine is given a partial negative charge

  30. Table Talk • Label the location of the partial positive and partial negative charges in water.

  31. Dipole Moments • The creation of a polar compound leads to the concentration of charge at the poles of the element. • Indicate dipole moment with an arrow that starts at positive and goes to the negative end F F H H

  32. Bonding is a Spectrum • The difference in electronegativity tells us the type of bond that a compound has. • Don’t worry about exact values, you can do this qualitatively

  33. Around the World • Determine if the compounds around the room are ionic, polar covalent, or non-polar covalent

  34. Exit Ticket 1. Draw all the resonance structures for NO3–. Label the formal charges on all atoms. 2. Draw the Lewis structure for HCl. Draw the dipole moment on the compound

  35. Rate Yourself • Based on the exit ticket and your current level of understanding, rate yourself 1 – 4 on LT 2.1, 2.2, 2.3, 2.4, and 2.5

  36. Closing Time • You should read section 8.1 – 8.7 for Thursday/Friday • Answer questions 8.1, 8.4, 8.22, 8.24, 8.39, 8.41, 8.47, 8.48, 8.52, 8.63, and 8.64 for Thursday/Friday

More Related