1. FAIR USE STATEMENT: Please feel free to edit and use this presentation in your classroom. Please do not remove the credit line on the title page or republish the file in whole or in part as your own. Please do not distribute the file to individuals or at conferences or workshops. I am more than willing to share the presentation with anyone that contacts me at rhondaa@cox-internet.com. The images in the presentation are not original and therefore the presentation is distributed freely and only for classroom instruction. Rhonda Alexanderrhondaa@cox-internet.com

2. Rhonda Alexander 2002 Robert E. Lee High School, Tyler, TX Next why bonds

3. General All bonding forces are due to electrostatic charge. Opposite charges attract, Like charges repel. This diagram shows the attraction and repulsion between atoms: The outer ring (e-) is the electron cloud. The inner red ring is the nucleus. Next forming H 2 bond movie

5. Electronegativ ity Difference 0.0 0 0.6 5 0.9 4 1.1 9 1.4 3 1.6 7 1.9 1 2.1 9 2.5 4 3.03 Percent Ionic Character 0% 10 % 20 % 30 % 40 % 50 % 60 % 70 % 80 % 90% Percent Covalent Character 100 % 90 % 80 % 70 % 60 % 50 % 40 % 30 % 20 % 10% 0 to.40.40 to 1.67 1.67 and greater Difference in Electronegativity IONICPOLAR COVALENT NONPOLAR COVALENT

6. Trends in electronegativity Increases right because Z eff increases, which attracts electrons more strongly. Outermost electrons are in same shell (same n). Increases because as you go up valence electrons are closer to the nucleus (orbitals are smaller) so they are more strongly attracted to the atom.

7. Practice Rank these elements by electronegativity: Rank these elements by electronegativity: Co, O, Si, Sr

8. Practice Rank these elements by electronegativity: Rank these elements by electronegativity: least = Sr < Co < Si < O = most electronegative Increase

9. Next types

10. THREE TYPES OF BONDS Next type

11. Next metallic

12. Metallic bonding can be pictured as positive metal ions in a sea of freely- moving negative electrons (delocalized electrons) Metallic bonding is moderate to strong Occurs between metal atoms. Metallic bond Next ionic

13. Ionic bond An ionic bond may result from electron transfer An ionic bond may result from electron transfer In an ionic bond, electrons are not shared. In an ionic bond, electrons are not shared. Atoms are held together by electrostatic attraction between positive and negative ions. Atoms are held together by electrostatic attraction between positive and negative ions. NaF ·· ·· +  · F Na + –

14. Next lattice energy

15. Next Coulomb’s law

16. Shared electrons are in the outer shells of both atoms Shared electrons are in the outer shells of both atoms The valence (outer) shells of both of these H atoms now have 2 electrons. The valence (outer) shells of both of these H atoms now have 2 electrons. Covalent bond ·· H Next covalent

17. Next polarity

18. POLAR COVALENT NONPOLAR COVALENT Next polarity

19. Next bond type practice

20. Practice Referring only to a periodic table, classify these bonds as ionic, polar covalent or nonpolar covalent Referring only to a periodic table, classify these bonds as ionic, polar covalent or nonpolar covalent S–S S–S N–F N–F Sn–Si Sn–Si Mg–O Mg–O Si–P Si–P Ni–S Ni–S C-H C-H Cs–F Cs–F Next $ %

21. Polar covalent bonds More electronegative partial negative charge Less electronegative partial positive charge ·· – F H ++ Next bonding pairs

22. Covalent bond Bonding electron pairs form the bond Bonding electron pairs form the bond Nonbonding electron pairs are called lone pairs Nonbonding electron pairs are called lone pairs ·· FF ·· +  · F F – F F or Next multiple

23. Multiple bonds Atoms can share more than two electrons Atoms can share more than two electrons single bond F 2 double bond O 2 triple bond N 2 O=OO=O ·· NNNN – F F Next strength

24. Multiple bonds are fatter and stronger N 2 O 2 F 2 N 2 O 2 F 2 triple bonddouble bondsingle bond Next 