1 / 18

How to draw Lewis dot structures for covalent compounds Text section 12.3

How to draw Lewis dot structures for covalent compounds Text section 12.3. Review. Valence e - ’s = only outside shell (s & p orbitals only) Lewis structures - show only valence e - ’s. How to draw a shared pair of electrons. (representation). More than one way to share electrons.

bruno-johnston
Download Presentation

How to draw Lewis dot structures for covalent compounds Text section 12.3

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. How to draw Lewis dot structures for covalent compoundsText section 12.3

  2. Review • Valence e-’s= only outside shell (s & p orbitals only) • Lewis structures-show only valence e-’s

  3. How to draw a shared pair of electrons (representation)

  4. More than one way to share electrons. H2 F2 O2 N2 H-H or H H = a single bond

  5. More than one way to share electrons: H2 F2 O2 N2 H-H F-F O=O NΞN single double triple H-H F-F O=O NΞN

  6. Bond length and bond strength • More electrons shared between nuclei = • Shorter (bonds) • Stronger (bonds) • Double & triple bonds don’t affect molecular shape.

  7. Steps for drawing Lewis dot structures for covalent compounds

  8. Find the sum of the valence electrons for the entire molecule • ( if a cation, subtract one electron from the total) • ( if an anion, add one electron to the total) • Divide the sum of valence electrons by 2 to find the number of electron pairs • Begin placing electron pairs between the central atom and the ligands • Continue placing the electron pairs around each ligand until the octet rule has been satisfied (or duet in Hydrogen’s case) • Place any leftover electron pairs on the central atom ( which causes the molecule to bend further) • Check to make sure all atoms are satisfied (octet/duet), if not, try a multiple bond.

  9. Example 1 NH3 • Valence electrons = 8 • Divide by 2 to find # of pairs 8/2 = 4 pairs e- • Place pairs between the central and all ligands • Give the ligands an octet of e-or a duet • Leftover pairs go back on the central • Check for duets or octets for all atoms • If not, use multiple bonds

  10. Example 2 H2S

  11. Example 3 CO2

  12. Example 4 HCN

  13. Example 5 NBr3

  14. Example 6 SO32-

  15. Example 7 NH4+

  16. Valence Shell Electron PairReplusion=VSEPR

  17. Resonance • 2 or more Lewis structures: Real = average • See nitrate on page 420 (for example) • For shape: any Lewis structure will do.

  18. Homework • Text pg. 421 a-i • Complete VSEPR prelab (if we decide to do it…)

More Related