1 / 11

Lewis Structures electron dot structures for molecules

Lewis Structures electron dot structures for molecules. 5 rules for Lewis Structures Find the total # of valence electrons for the molecule Find the center atom (the element with the least # of atoms)

aperaza
Download Presentation

Lewis Structures electron dot structures for molecules

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. Lewis Structures electron dot structures for molecules

  2. 5 rules for Lewis Structures Find the total # of valence electrons for the molecule Find the center atom (the element with the least # of atoms) Draw bonds. Connect the other atoms to the center atom. Then subtract 2 electrons from the total # of valence electrons for each bond drawn. ( when we do an example this will become clear)

  3. 5 rules for Lewis Structures Distribute electrons around each atom to give a total of 8 electrons except H, Al, B, & Be If there are not enough electrons to give 8 around each atom, create double & triple bonds.

  4. Example 1:CF4 1. Total valence electrons = C + F 4 + 4(7) = 32 valence electrons 2. Center atom (least # of atoms) = C write C in the middle draw bonds (lines) to connect four F atoms F F C F F 3. Subtract 2 times (# of bonds)- each bond uses 2 electrons 32 – 2(4) = 24 electrons 24 electrons left to distribute around the F atoms one line means 2 electrons

  5. 4. Distribute left over 24 electrons to F F F — C — F F C needs no electrons because it has 4 bonds (octet) Now each F has 8 electrons around it (octet) This is the Lewis structure of CF4 It shows how many bonds and where e- are located Lone pairs of e- not involved in bonding

  6. Example 2: NH3 5 + 3(1) = 8 electrons H can have 2 e- (H is one of the exceptions) 8 – 2(3 bonds) = 2 electrons left for N H H N H

  7. Example 3: H2S 2(1) + 6 = 8 electrons H can have 2 e- (H is one of the exceptions) 8 – 2(2 bonds) = 4 electrons left for S H H S

  8. Ions • With Ions we add or take away electrons Example 4: PO43- Gained 3e- 5 + 4(6) + 3 = 32 electrons 32-2(4 bonds) = 24 electrons to distribute • Put ions in brackets and the charge on the outside 3- O O O P O

  9. Double Bonds Example 5: CO2 - What’s wrong with Carbon? Carbon does not have 8 electrons, so electrons will bond differently O – C – O Now carbon and oxygen have 8 electrons O – C – O “Double Bond”

  10. Incomplete Octet Example 6: BCl3 3 + 3(7) = 24 electrons 24 – 2(3 bonds) = 18 electrons left for Cl Boron does not have 8e- around it. It is incomplete but it is okay; it is one of our exceptions. Cl Cl B Cl

  11. Triple Bond Example 8: CO 4 + 6 = 10 electrons 10 – 2(1 bond) = 8 electrons left for C or O If we try putting 4 electrons on C and 4 on O, then they will each only have 6 electrons. Try doubling or tripling the bonds if you do not have an octet. C – O

More Related