1. Chemical Bonding

2. Chemical Bond
mutual electrical attraction between nuclei and valence electrons of different atoms that binds the atoms together

3. Chemical Bond

4. Types of Chemical Bonds
Ionic bonding = results from the electrical attraction between cations and anions; one atom gives its electrons to another atom (metal and nonmetal)

5. Types of Chemical Bonds

7. Types of Chemical Bonds
Covalent bonding = results from the sharing of electron pairs between two atoms
(2 nonmetals)

8. Types of Chemical Bonds

10. Types of Chemical Bonds
Polar covalent bond = electrons are shared unequally by bonded atom resulting in an unbalanced charge distribution

11. Determining Bond Type

12. Types of Chemical Bonds
Nonpolar covalent bond = electrons are shared equally by the bonded atoms, resulting in balanced distribution of charge

13. Types of Chemical Bonds

14. Types of Chemical Bonds

15. Determining Bond Type
Based on electronegativty

16. Determining Bond Type
Bond type can be estimated by calculating the difference in elements’ electronegativities
Ionic bonds:
Polar covalent: 0.31 – 1.70
Nonpolar covalent:

17. Practice Problem
Use the electronegativity differences to determine bonding in the following elements
H and S , Ca and Cl, I and I

18. More Practice Problems
Use the electronegativity differences to determine bonding in the following compounds; then describe each bond type.
Cl and Br, Cs and S, and P and O

19. Valence Electrons
the electrons in the highest occupied energy level of an element’s atoms
determine the properties of elements
equals the group number
used in bonding

20. Electron Dot Structures
diagrams that show the valence electrons as dots placed around an element’s symbol

21. Electron Dot Structures

22. Octet Rule
atoms bond and achieve electron configurations of a noble gas, ns2np6…
a set of 8 electrons to become stable

23. Octet Rule
Atoms of metallic elements tend to lose electrons to make a complete octet in the next lowest energy level

24. Octet Rule
Atoms of nonmetallic elements gain or share electrons with another element to achieve a complete octet

25. Properties of Ionic Compounds
Crystalline solids at room temperature
conduct electric current when dissolved in water
arranged in repeating 3-D patterns

26. Formation of Ionic Compounds
1.Draw Electron Dot Structure
2. Show give/take of e-
3. State what happened
4. Write the formula

27. Formation of Ionic Compounds
Show the formation of the bond between
Na and Br
Ca and Cl
Al and S

30. Formation of Ionic Compounds
Show the formation of the bond between
Al + Br, K + O, Mg + N, Li + I, Ca +P

31. Covalent Bonding
electrons are shared between nonmetals in groups 4A,5A,6A,7A

32. Covalent Bonding
Rules for drawing Lewis structures
1. Add valence electrons for all atoms

33. 2. Write symbols for atoms to show arrangement of atoms
Covalent Bonding
2. Write symbols for atoms to show arrangement of atoms
C is always in the middle
H is always outside
Least electronegative atom is in the middle

34. Covalent Bonding
3. Complete the octets of atoms bonded to central atom, except H
4. Place leftover electrons on central atom
5. If central atom is incomplete try a multiple bond

35. Single Covalent Bonding
bond in which two atoms share a pair of electrons
Ex] H2

36. Single Covalent Bonding
Structural Formulas - a shared pair of electrons are represented by a dash

37. Single Covalent Bonding
Examples:
Fluorine, Water
Ammonia,
Carbon tetrachloride
GeF4, PCl3

38. Double and Triple Covalent Bonding
Double bonds: share 2 pairs of electrons, (=)
Triple bonds: share 3 pairs of electrons

39. Double and Triple Covalent Bonding
Examples: N2
CO2

40. Practice
Br2
SiCl4
HCl O2
HCN CO

41. Resonance Structures structures that occur when
it is possible to write 2 or more valid lewis structures that have the same number of electron pairs for a molecule or ion
(O3)

42. Polyatomic Ions
covalently bonded
Examples:
NH4+
SO32-
ClO3-

43. Exceptions to the Octet Rule
Some substances do not obey the octet rule and can have an incomplete or expanded octet
BF3, PCl5, SF6, XeF4

44. Practice
SO2
SO42-
H3O+
OH-
BH3
XeF2
H2O2
NCl3
NO3-

45. Molecular Geometry
Shape of a molecule is determined by the bond angle which is based on the number of electron domains in the molecule

46. Molecular Geometry
A pair of electrons, single, double, and triple bonds each consist of 1 electron domain

47. Molecular Geometry

48. Molecular Geometry
To Predict Shapes:
1. Draw Lewis structure and count e-d’s
2. Predict bond angles and molecular geometry using table

49. Molecular Geometry

51. Molecular Geometry
Examples:
CO2
BF3
CBr4
PCl5
SF6

52. Molecular Geometry Practice: Predict Shape and Angle BeF2 BCl3 SiH4
AsF5
NO3-
ClO4-

53. Intramolecular vs. Intermolecular
Intramolecular Forces – forces within molecules – chemical bonds
Intermolecular Forces – forces between molecules – IMF’s

54. Intermolecular Forces
Broken during phase change
The stronger the IMF, the higher the mp/bp

55. Types of Intermolecular forces
hydrogen bonding:
attraction between the H atom in a molecule with H-F, H-O, or H-N and an unshared electron pair on N,F, or O

56. Types of Intermolecular forces
hydrogen bonding:

57. Properties of Water

58. Unique Properties of Water
1. Hydrogen bonds cause density of solid H2O to be less than liquid H2O, so ice floats.
2. Hydrogen bonds cause high surface tension in water.

59. Properties of Water