1. Covalent Bonding Between nonmetals Between nonmetals Share valence electrons between atoms Share valence electrons between atoms Electron clouds overlap Electron clouds overlap Ex:H 2 O CH 4 NH 3 CO 2

2. Electronegativity Difference in EN smaller than in ionics and is usually < 1.7 Difference in EN smaller than in ionics and is usually < 1.7 Ex: HCl Ex: HCl H = 2.2Cl = 3.2 Difference = 1.0

3. Bond Polarity Polar Bond: there is a difference in EN values (unequal sharing) Polar Bond: there is a difference in EN values (unequal sharing) Ex: H Cl Ex: H Cl EN=2.2 EN=3.2

4. NonPolar Bond:no difference in EN values. (equal sharing) NonPolar Bond:no difference in EN values. (equal sharing) Ex: O 2, N 2, Cl 2, H 2 (all the diatomics!)

5. Comparing Bond Types

6. Single, Double, Triple Bonds Atoms can share single double or triple bonds between them. Atoms can share single double or triple bonds between them. Each bond represents a shared pair of electrons. Each bond represents a shared pair of electrons. http://youtu.be/1wpDicW_MQQ http://youtu.be/1wpDicW_MQQ http://youtu.be/1wpDicW_MQQ

7. Molecular Formulas Covalent compounds are molecules. Covalent compounds are molecules. Made up of all nonmetals. Made up of all nonmetals. Molecular formulas: show actual number of atoms of each element present in compound Molecular formulas: show actual number of atoms of each element present in compound Ex: H 2 O 2 hydrogen atoms and 1 oxygen

8. Structural Formulas Show how the atoms are bonded together in a covalent molecule. Show how the atoms are bonded together in a covalent molecule. Use “lines” to show covalent bonds Use “lines” to show covalent bonds

9. Empirical Formulas Show simplest whole number ratio of atoms or ions in the compound. Show simplest whole number ratio of atoms or ions in the compound. Ex: MgCl 2 1 : 2 ion ratio Ionic compounds are “salts” or ionic crystals. Ionic compounds are “salts” or ionic crystals. All ionic compounds have empirical formulas All ionic compounds have empirical formulas

10. You can simplify some molecular formulas to make them empirical ratios Ex: C 6 H 12 O 6 Simplest ratio of atoms CH 2 O

11. Naming Covalent Compounds Prefix system indicates number of atoms of each element Mono Mono Di Di Tri Tri Tetra Tetra Penta Penta Hexa Hexa Hepta Hepta Octa Octa Nona Nona Deca Deca

12. Molecule vs. Ionic Crystal CH 4 = 5 atoms in moleculeNaCl = 1:1 ion ratio

13. Drawing Covalent Molecules Lewis Structures

14. See page 10 in Bonding Packet 1. Count total valence e - in the molecule 2. Draw molecule with single bonds between atoms (then subtract these e- from total) 3. Evenly distribute remaining e - in pairs to all atoms in molecule that still need e- 4. Check to see if all obey octet rule (Remember Hydrogen is fine with 2 e - ) 5. If deficient, shift over free e - pairs to make double or triple bonds as needed.

15. Draw NH 3 Draw NH 3 Draw H 2 O Draw H 2 O Draw CH 4 Draw CH 4

16. Crash Course Chemistry: Lewis Structures: http://www.youtube.com/wat ch?v=a8LF7JEb0IA

17. Drawing Polyatomic Ions Covalently bonded atoms with a group charge Covalently bonded atoms with a group charge Follow same steps for drawing covalents. Follow same steps for drawing covalents. Add or subtract electrons from total valence depending on charge. Add or subtract electrons from total valence depending on charge. Draw brackets around ion and indicate charge. Draw brackets around ion and indicate charge. Ex:(SO 4 ) -2 Ex:(SO 4 ) -2 6 + 4(6) + 2 = 32 electrons

18. VSEPR and Molecular Shape To predict molecular shape, assume valence electrons repel each other. To predict molecular shape, assume valence electrons repel each other. Molecule adopts 3D geometry that minimizes this repulsion. Molecule adopts 3D geometry that minimizes this repulsion. Valence Shell Electron Pair Repulsion (VSEPR) theory. Valence Shell Electron Pair Repulsion (VSEPR) theory.

19. Predicting Molecular Geometries Draw Lewis structure Draw Lewis structure Count total number of electron pairs around the central atom (both shared and unshared) Count total number of electron pairs around the central atom (both shared and unshared) Arrange electron pairs to minimize e  repulsion Arrange electron pairs to minimize e  repulsion Multiple bounds count as one bonding pair Multiple bounds count as one bonding pair

20. Molecular Shapes Regents Shapes to Know: Regents Shapes to Know: Tetrahedral Tetrahedral Pyramidal Pyramidal Bent Bent Linear Linear

21. Is a Molecule Polar? If the centers of negative and positive charge do not coincide, then the molecule is polar. If the centers of negative and positive charge do not coincide, then the molecule is polar.

22. Look for Symmetry Polar Molecules: Polar Molecules: Have polar bonds and are not symmetrical Have polar bonds and are not symmetrical Positive & negative “partial charges” don’t overlap Positive & negative “partial charges” don’t overlap They have a “dipole moment” They have a “dipole moment” Nonpolar Molecules Nonpolar Molecules Have nonpolar bonds Have nonpolar bondsOR Have polar bonds and are symmetrical Have polar bonds and are symmetrical Centers of positive & negative charge overlap Centers of positive & negative charge overlap

23. Example: In CO 2, the polarity of each C-O bond is cancelled because the molecule is linear. In H 2 O, the polar H-O bonds do not cancel because the molecule is bent.

24. Tetrahedral Tetrahedral Has 4 atoms bonded (no free pairs) Has 4 atoms bonded (no free pairs)

26. Symmetry? Depends on what atoms are attached. Can be polar (asymmetrical) or nonpolar (symmetrical)

27. Pyramidal Pyramidal Three atoms bonded (one free pair) Three atoms bonded (one free pair)

28. Symmetry? All pyramids are asymmetrical. All pyramids are asymmetrical. These molecules are always POLAR! These molecules are always POLAR!

29. Bent Bent Two atoms attached (2 free pair) Two atoms attached (2 free pair) The 2 free pair make it bent and not linear. These are always asymmetrical so are always polar. H2OH2O

30. Hey, Water is Polar!!!!! Never forget this!!!

31. Without polar water NO LIFE!! The polar nature of water molecules allows them to bond to each other in groups and is associated with the high surface tension of water.surface tension The polar nature of the water molecule has many implications. It causes water vapor at sufficient vapor pressure to depart from the ideal gas law because of dipole-dipole attractions. This can lead to condensation and phenomena like cloud formation, fog, the dewpoint, etc.vapor pressureideal gas lawdewpoint It also has a great deal to do with the function of water as the solvent of life in biological systemssolvent of life

32. Linear Linear 2 atoms in molecule 2 atoms in molecule Ex:ClCl (nonpolar bond, sym., nonpolar molecule) Ex:ClCl (nonpolar bond, sym., nonpolar molecule) HBr (polar bond, asym., polar molecule) 3 atoms in molecule 3 atoms in molecule Ex: CO 2

33. GOOD FOR REVIEW Crash Course Chemistry: Polarity of Molecules Crash Course Chemistry: Polarity of Molecules http://www.youtube.com/watch?v=PVL24HAesnc http://www.youtube.com/watch?v=PVL24HAesnc http://www.youtube.com/watch?v=PVL24HAesnc Dipole Moment: Dipole Moment: https://www.khanacademy.org/science/organic- chemistry/gen-chem-review/electronegativity- polarity/v/dipole-moment https://www.khanacademy.org/science/organic- chemistry/gen-chem-review/electronegativity- polarity/v/dipole-moment https://www.khanacademy.org/science/organic- chemistry/gen-chem-review/electronegativity- polarity/v/dipole-moment https://www.khanacademy.org/science/organic- chemistry/gen-chem-review/electronegativity- polarity/v/dipole-moment

34. Properties of Covalent Compounds

35. Melting Point Lower than Ionics Lower than Ionics To melt, you are only separating the weak bonds between molecules (not within). To melt, you are only separating the weak bonds between molecules (not within).

36. Melting Point Polar Molecules (dipoles/”mini-magnets”): Polar Molecules (dipoles/”mini-magnets”): Have higher melting points than non-polars because they are harder to separate.

37. Solubility Polar Molecules dissolve in polar solvents as they are attracted to them Polar Molecules dissolve in polar solvents as they are attracted to them like H 2 O, CHCl 3, NH 3 etc. like H 2 O, CHCl 3, NH 3 etc. Non-polar Molecules dissolve in non-polar solvents Non-polar Molecules dissolve in non-polar solvents like hexane, CCl 4 like hexane, CCl 4 “Like Dissolves Like”

38. Oil and water don’t mix! How does soap work? How does soap work?

39. Conductivity Covalent Molecules do not conduct well as they do not form ions. Covalent Molecules do not conduct well as they do not form ions. They are “nonelectrolytes” They are “nonelectrolytes” Except Acids!!!! Except Acids!!!! Acids are covalently bonded but in water (aqueous) they will ionize and conduct current. Acids are covalently bonded but in water (aqueous) they will ionize and conduct current. (Acids are not on this test) (Acids are not on this test)

40. Decompose If the heat gets high enough covalent compounds will break down and decompose. If the heat gets high enough covalent compounds will break down and decompose. (Remember the lab, sugar melted first, then it burned and turned into black carbon) (Remember the lab, sugar melted first, then it burned and turned into black carbon)

41. Other Types of Covalent Bonds

42. Coordinate Covalent Bonding Covalent bond in which one of the bonding atoms donates both of the electrons to the bond. Covalent bond in which one of the bonding atoms donates both of the electrons to the bond. The other atom donates nothing. The other atom donates nothing. Ex: Forming Hydronium Ion

43. To form this type of bond you must have: To form this type of bond you must have: A molecule with a free pair of electrons A molecule with a free pair of electrons Something that needs to gain 2 electrons Something that needs to gain 2 electrons H +1

44. Ex: Forming Ammonium Ion

45. Network Solids Giant network of covalently bonded atoms. Giant network of covalently bonded atoms. Large macromolecules Large macromolecules Extremely strong structures Extremely strong structures Unusually high M.P. Unusually high M.P. Do not dissolve Do not dissolve Diamonds are a giant network of carbon atoms.

46. “Buckyball” Ex: C (s) (graphite, diamond, buckyball), SiO 2 (quartz), GeO 2

47. Bonding in Pure Metals

48. Metallic Bonding Happens in or alloys. Happens in pure metals or alloys. Ex:Mg, Fe, Brass, Au, Ni, Cu Ex:Mg, Fe, Brass, Au, Ni, Cu “Delocalized” valence electrons move about between all the metal atoms. “Delocalized” valence electrons move about between all the metal atoms. http://www.youtube.c om/watch?v=XHV9L zCH2KA

50. Metallic Bonding Properties Conducts heat and electricity very well Conducts heat and electricity very well Conducts as a solid too! Does not dissolve in solvents Does not dissolve in solvents Malleable and Ductile Malleable and Ductile Relatively high melting point. Relatively high melting point. Higher MP than covalents. Higher MP than covalents. Similar MP to most ionics Similar MP to most ionics Properties 2 minutes: http://www.youtube.co m/watch?v=srxNJ03W_ qM

51. Metallic Bonding http://www.drkstreet.com/resources/metallic-bonding- animation.swf http://www.drkstreet.com/resources/metallic-bonding- animation.swf http://www.drkstreet.com/resources/metallic-bonding- animation.swf http://www.drkstreet.com/resources/metallic-bonding- animation.swf

52. EXTRA VIDEO LINKS FOR FUN AND LEARNING Ionic vs. Covalent Bonding Ionic vs. Covalent Bonding http://youtu.be/QqjcCvzWwww http://youtu.be/QqjcCvzWwww http://youtu.be/QqjcCvzWwww http://youtu.be/yjge1WdCFPs http://youtu.be/yjge1WdCFPs http://youtu.be/yjge1WdCFPs Electronegativity Electronegativity http://youtu.be/Kj3o0XvhVqQ http://youtu.be/Kj3o0XvhVqQ http://youtu.be/Kj3o0XvhVqQ Bonding Dance Party Bonding Dance Party http://www.youtube.com/watch?v=wBCmt_pJTRA http://www.youtube.com/watch?v=wBCmt_pJTRA http://www.youtube.com/watch?v=wBCmt_pJTRA It’s a chemical bond baby” It’s a chemical bond baby” http://youtu.be/wWUYHHo-zB0 http://youtu.be/wWUYHHo-zB0 http://youtu.be/wWUYHHo-zB0 Dancin Queen (Ionic/Covalent Bonds) Dancin Queen (Ionic/Covalent Bonds) http://youtu.be/BCYrNU-7SfA http://youtu.be/BCYrNU-7SfA http://youtu.be/BCYrNU-7SfA Isn’t it Ionic Isn’t it Ionic http://youtu.be/rwRtfrgJL5E http://youtu.be/rwRtfrgJL5E http://youtu.be/rwRtfrgJL5E