1 / 16

Lewis Structures

Lewis Structures. Representing the electron placement in molecules. Review. A molecular compound results when non-metal atoms and/or metalloid atoms share electrons in order to reach their octets. Each covalent bond involves 1 pair of electrons.

connor-stevens
Download Presentation

Lewis Structures

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 Representing the electron placement in molecules

  2. Review • A molecular compound results when non-metal atoms and/or metalloid atoms share electrons in order to reach their octets. • Each covalent bond involves 1 pair of electrons. • Atoms can sometimes form multiple bonds by sharing more than 1 pair of e-. • 1 double bond = 2 pairs of e- • 1 triple bond = 3 pairs of e-

  3. Review • Electron dot diagrams show the number of valence electrons surrounding an atom. • 1 – 8 valence electrons H B C N O F Si P S Cl As Se Br Te I

  4. Lewis Structures • Lewis Structure – shows the placement of e- in a molecule or polyatomic ion.

  5. How to Draw Lewis Structures • Determine the number of electrons • Needed to give each atom an octet. • All atoms need 8 valence electrons, except: • hydrogen needs only 2. • boron needs only 6. • Available from the atoms’ valence e-. • All valence electrons for all atoms in structure. • Shared = Needed – Available

  6. How to Draw Lewis Structures • Choose the central atom for the structure. • NEVER hydrogen. • Carbon if it’s in the formula. • Least EN element.

  7. How to Draw a Lewis Structure • Draw structure • Write symbol of central atom. • Arrange other atoms around it. • Show shared e- as pairs of dots between atoms. • If you have leftover shared e-, make double bonds but never to hydrogen. • Show other available e- as pairs of dots around atoms.

  8. How to Draw Lewis Structures • Check your structure • Is the right atom in the center? • Have the correct number of e- been shared? • Are all available e- shown? • Is the octet rule satisfied for every atom (except H and B?)

  9. How to Draw Lewis Structures • Draw the Lewis structure for H2O. • Needed: • 2 x hydrogen = 2 x 2 needed = 4 needed • 1 x oxygen = 1 x 8 needed = 8 needed • Total needed e- = 12 • Available: • 2 x hydrogen = 2 x 1 available = 2 available • 1 x oxygen = 1 x 6 available = 6 available • Total available e- = 8 • Shared: • 12 – 8 = 4 shared e- (2 pairs)

  10. H H O O H H or How to Draw Lewis Structures • What atom should be in the center? • Never hydrogen. • Oxygen is in the center. • Draw the structure placing O in the center. • Put shared pairs between atoms. • Complete the octets of all atoms (except H) • Check your structure.

  11. O C O O C O How to Draw Lewis Structures • Draw the Lewis structure of CO2. N = 24 e- A = 16 e- S = 8 e-

  12. H C N How to Draw Lewis Structures • Draw the Lewis structure of HCN. N = 18 e- A = 10 e- H C N S = 8 e-

  13. O O S O O O S O How to Draw Lewis Structures • Draw the Lewis structure of SO3. N = 32 e- A = 24 e- S = 8 e-

  14. Polyatomic Ions • You can draw the Lewis structure of a polyatomic ion just as you do for a neutral molecule. • Two differences: • Add or subtract e- from the available number to account for the charge of the ion. • Place the finished drawing in brackets and write the charge outside the brackets.

  15. -3 O O P O O How to Draw Lewis Structures • Draw the Lewis structure for PO4-3. N = 40 e- A = 32 e- S = 8 e-

  16. -2 O O C O How to Draw Lewis Structures • Draw the Lewis structure for CO32-. N = 32 e- A = 24 e- S = 8 e-

More Related