1. Chemical Bonding 1

2. Video

3. Chemical Bonding
Atoms lose, gain, or share electrons to have an octet (8e-) in its outer energy level.

4. Types of Bonding
Ionic
Covalent
Metallic

5. Ionic Bonding Transfer of electrons
Metal (loses e-) forms a + ion nonmetal (gains e-) forms a negative ion
Ex: NaCl, KBr, KNO3

7. Ionic Bonding Example: Na and Cl
In ionic bonding one atom has a stronger attraction for electrons than the other, and “steals” an electron from a second atom e– 1) 2) Na Cl 3)
Cl–
Na+

8. Properties of Ionic Compounds
Crystalline solids
High melting point
Brittle
Conducts electricity in molten form and when dissolved in water
Forms a crystal lattice
Held together by electrostatic attraction (opposite charges)

9. Crystal Lattice

10. Sodium and Chlorine
NaCl

11. Calcium and Chlorine
CaCl2

12. Potassium and Sulfur
K2S

13. Covalent (Molecular) Bonding
Share e-
Nonmetals only
Ex: H2O, CCl4

15. Electronegativity Measure of the attraction for a shared electron.
Which family would have the highest electronegativity?
Which element would have the highest electronegativity?

16. Electronegativity
increases
decreases
Don’t include the noble gases

17. Electronegativities and Bond Type
The type of bond or degree of polarity can be calculated by finding the difference in electronegativity of the two atoms that form the bond.

18. Two types of covalent bonds
Nonpolar bond- share e- equally
Ex: Cl2, O2
Polar bond- unequal sharing of e-, 2 different nonmetals
Ex: C-O, N-H

19. Electronegativity Difference
Used to determine if a bond is ionic or covalent
Atoms that have electronegativity differences greater than 1.7 form ionic bonds. Ex: Na-Cl
If the difference is 0 to 0.4 the bond is nonpolar covalent. Ex: Cl2.
Atoms that have electronegativity differences less than 1.7 and greater than 0.4 form polar covalent bonds. Ex: H-O
The greater the electronegativity difference the more polar the bond will be. 19

20. Electronegativity Difference
nonpolar polar ionic

21. Examples Classify as polar, nonpolar, or ionic. P-Cl polar 2. Cl-Cl
3. Ca-F
ionic

22. Polar Bonds
Partial positive charge
Partial negative charge
F has a higher electronegativity than H. H and F are sharing the electrons, but
F has a greater pull on the shared electrons. F wins the “tug of war” and pulls
the electrons closer giving F a partial negative charge. The electrons are pulled
away from the H atom. This gives H a partial positive charge. These are NOT
complete charges like in an ionic bond.

23. Polar, Nonpolar and Ionic Bonds

24. Video

25. PROPERTIES OF COVALENT COMPOUNDS
Solids, liquids and gases
Lower melting points than ionic compounds
Nonconductors (nonelectrolytes)
All nonmetals
Ex: C12H22O11 (solid) H2O (liquid)
CO2 (gas)

26. Octet Rule Octet rule- atoms form bonds to have 8 valence electrons
Exception: H (2 e- )
B (6 e-)

27. Lewis Dot Structures F2

28. MATH METHOD
Count the total # of e- needed to satisfy the octet rule. (NEED)
Count the total # of valence e-. (HAVE)
Subtract #2 from #1 and divide by 2. This equals the # of bonds.
Make sure every atom obeys the octet rule.

29. Bond Energy BOND ENERGY – energy required to break a bond.
Triple bond has the _____________ bond energy and a single bond has the ____________ bond energy.
Triple bond has the _____________ bond length and a single bond has the ____________ bond length.

30. Resonance
Resonance Structures- occur when more than 1 Lewis structure can be drawn for a molecule.
Ex: CO3-2
SO2

31. Exceptions Exceptions to the octet rule: H ______ B_______
Be __________
Expanded Octet: _______than 8 e- on the central atom (Honors)

32. Examples (Honors)
Ex: PCl5 SF6

33. Video

34. MOLECULAR SHAPES VSEPR MODEL Bonds are made up of e-
Bonds repel each other
Bonds will spread out around the central atom to be as far apart as possible
Lone pairs of electrons repel more than bonds repel each other
Count the number of bonded atoms and the number of lone pairs on the CENTRAL atom to determine the shape.

35. Molecular Shapes
Two atoms bonded to central atom. Can be single, double, or triple bonds.
Ex: BeH2
Shape: linear
Bond angle: 180°

36. Linear

37. Linear

38. Molecular Shapes
2. Three atoms bonded to central atom. Ex: BH3 Shape: trigonal planar Bond angle : 120°

39. Trigonal Planar

40. Trigonal Planar
Ex: CH2O

41. Molecular Shapes
3. Two atoms and one or two lone pairs on the central atom.
Ex. H2O
Shape: bent
Bond angle: 104.5°

42. Bent

43. Bent
Ex: SO2

44. Molecular Shapes
4. Three atoms and one lone pair on the central atom. Ex: NH3 Shape: Trigonal Pyramid Bond angle: 107°

45. Trigonal Pyramid

46. Molecular Shapes
5. Four atoms around the central atom. Ex: CH4 Shape: Tetrahedral Bond angle: 109.5°

47. Tetrahedral

48. (Honors) Additional Shapes
6. Five atoms around the central atom. Ex: PCl5 Shape: Trigonal Bipyramidal Bond angle: 90° and 120°

49. Trigonal Bipyramidal

50. One Last Shape
7. Six atoms around the central atom. Ex: SF6 Shape: Octahedral Bond angle: 90°

51. Octahedral

52. Polarity of Molecules
Nonpolar Molecule- equal distribution of electrons. Symmetrical around the central atom. Must be the same atom around the central atom.

53. Nonpolar Molecule with Polar Bonds

54. Polar Molecule – unequal electron distribution
Polar Molecule – unequal electron distribution. Not symmetrical around the central atom.

55. Polar Molecule

56. Polar Molecule

57. Hybridization (Honors)
Examples:
Be in BeCl2
B in BCl3
C in CH4
P in PCl5
S in SF6

58. How to Determine Hybridization
COUNT THE ELECTRON GROUPS AROUND AN ATOM
DOMAINS- # OF ATOMS BONDED TO A CENTRAL ATOM + # UNSHARED PAIRS OF ELECTRONS

59. # OF DOMAINS
HYBRIDIZATION 2 sp 3
sp2 4
sp3 5
sp3d 6
sp3d2

60. Molecular Shape
# Domains
Hybridization
Examples
Linear 2 sp
CO2
Trigonal planar 3
sp2
BCl3
Bent
3 (2 bonds + 1 unshared pair)
SO2
Tetrahedral 4
sp3
CH4
4 (2 bonds + 2 unshared pairs)
H2O
Trigonal pyramid
4 (3 bonds + 1 unshared pair)
NH3
Trigonal bipyramidal 5
sp3d
PCl5
Octahedral 6
sp3d2
SF6

61. Metallic Bonding 61

62. Metallic Bonding
Metallic Bonds are a special type of bonding that occurs only in metals
Characteristics of a Metallic Bond.
A metallic bond occurs in metals. A metal consists of positive ions surrounded by a “sea” of mobile electrons.
Good conductors of heat and electricity
Great strength
Malleable and Ductile
Luster
This diagram shows how metallic bonds might appear 62