1. HONORS CHEMISTRY
Oct 30, 2013

2. Chemical Bonding Types of bonds and types of substances
Ionic
Covalent
Metallic
The type of bond between atoms is partially responsible for the properties of the substance.

3. Notes handout

4. Why do atoms form bonds? Lewis Dot Diagrams Octet Rule
Atoms tend to gain, lose, or share electrons in order to acquire a full set of valence electrons.
Used to illustrate an atoms valence electrons
Used to illustrate how electrons rearrange during chemical reactions

5. Lewis Symbols and the Octet Rule
Lewis Symbols: The number of valence electrons available for bonding are indicated by unpaired dots.

6. Lewis Symbols These symbols are called Lewis symbols.
We generally place the electrons on four sides of a square around the element symbol.

7. Why do atoms form bonds? Lewis Dot Diagrams Octet Rule
Atoms tend to gain, lose, or share electrons in order to acquire a full set of valence electrons.
Used to illustrate an atoms valence electrons
Used to illustrate how electrons rearrange during chemical reactions
Na Xe P

8. Lewis Dot Practice O Te Ca Ba Ne I Cs

9. Ions and Ionic Compounds
Ions are formed by adding or subtracting electrons from a neutral atom or molecule.
Cation: positive charge (remove electrons) Na+
Anion: negative charge (add electrons) Cl-
Ions may be monatomic or polyatomic
03m07an1&2

10. Types of Ions Monatomic ions
Single atom ions
O 2-
Na+
Al3+
Polyatomic ions (refer to back of P. table)
More than one atom ions
NH4 +
OH –
SO4 2-

11. Predicting Ionic Charges
Electron Counts of Stable Ions
Ions tend to have the same number of electrons as the nearest noble gas.
Transition metals are not as predictable, but +2 and +3 are common.
3 transition metals with fixed charge (Ag+1, Zn+2 Cd+2)
ion_charges.exe

12. Main Group Elements
Note periodicity of charges

13. Transition Elements
Not periodic; +2 and +3 common

14. Charges and Formulas of Oxoanions
Oxoanions generally have the same charge as the simple anion of the same nonmetal.
Related to position in the periodic table; note exceptions for B, C, N
Polyatomic Ions
tend to reflect
the charge of the base element

15. Practice on Ionic Charges
Pair Share: What is the common charge of an ion of potassium, K?
Pair Share: What is the common charge of an ion of sulfur, S?

16. Why do atoms form bonds?
Ionic bond
Example
Lewis Dot diagram
A positively charged ion is attracted to a negatively charged ion.
A transfer of electrons
Metal and a Non-Metal
NaCl Na Cl Na Cl

17. Why do atoms form bonds? Mg, S Ca, Br Practice
Draw Lewis Dot Structure!!!
Metal Non-Metal

18. What holds Ionic bonds together?
Electrostatic Attraction
+ and - charge

19. Formation of an Ionic Compound
Vd02_007.mov

20. Properties of Ionic Bonds
Ionic bonds are very strong, so separating ions requires much energy
High melting points, boiling points
Crystals are hard and brittle
Electrical insulators when solid, electrical conductors when molten or dissolved in water
Demo:
electric_pickle.mov

21. Electrical Conductivity
Solid NaCl Liquid NaCl
03s11vd1

22. Structure and Properties
Why are crystalline solids brittle, whereas metallic solids are malleable?

23. Structure and Properties
Brittleness
brittle2.mov
maleable2.mov

24. Examples of Ionic Formulas
What is the formula of each of these compounds?

25. Writing Formulas for Ionic Compounds
Crisscross Method
Example
Ca and F
Write the element symbols for the cation and anion, with the cation on the left and the anion on the right.
Write each ion’s charge as a superscript.
Crisscross the two charges moving them downward diagonally from one superscript to the other subscript.

26. Writing Formulas for Ionic Compounds
Practice
Li and O
Mg and O
Ca and N
Mg and C

27. Practice Rewrite these incomplete formulas as correct formulas.
AlS CaP BaBr
Make formulas from the following ions:
Mg2+, OH Fe2+, PO43- Sc3+, O2-

28. Bonding with a partner You will receive a card with an ion.
You will find another person with the opposite charge from you.
You will write the ions on your paper and the formula they will create together.
Exchange cards and repeat the steps again until you fill up your paper.

29. Chemical Formulas Remember
Combine ions to obtain electrical neutrality
Ionic_Formula.exe

30. STOP

31. Naming Binary Ionic Fixed Charge Compounds (Formula  Name)
Example:
Li2O
Name the cation
Name the anion, changing the ending to ide
Lithium Oxygen + ide
Lithium Oxide
More examples:
NaCl
CaS
AlF3

32. Naming Binary Ionic Compounds
Name  Formula
Example:
Calcium Chloride
Ca +2 and Cl -1
CaCl2
Identify the ions involved
List the cation first and then the anion
Determine that charge of each ion involved
Balance the charges so the compound is neutral (criss-cross method).

33. Practice Write the structural formula for the following:
Hint: separate them into ions and then criss cross
Magnesium phosphide
Calcium iodide
Beryllium oxide

34. Naming Binary Ionic Compounds STOCK (Transitional Metals)
Formula  Name
CoCl2
Example:
Cobalt (II) chloride
Name the cation
Determine the charge of the anion
Based on the anion, what charge does the cation need to make the compound neutral.
Write the cation charge in parenthesis as a roman numeral
Name the anion.

35. Examples
Fe3P2
Cu2S
NiO

36. Naming Binary Ionic Compounds Stock (Name  Formula)
Example:
Calcium Chloride
Copper(II) Oxide
List the cation first and then the anion
Give the cation the charge stated in the name
Determine the charge of the anion
Balance the charges so the compound is neutral.
Ca +2 and Cl –1 CaCl2
Cu + 2 and O –2 CuO

37. Examples Copper (II) nitride Vanadium (II) oxide Zinc chloride
3 Special Transition Metals (do not require Roman numerals: fixed charge): Zn Cd Ag

38. Practice
Writing Formulas “Transition Metals (stock Method)” wksheet

39. Naming Ternary Molecular Structures
What is a Ternary Molecular Structure?
Example
MgSO4
Magnesium Sulfate
CuSO4 Copper (II) Sulfate
A molecule that has more than two elements.
A combination of a metal and a polyatomic ion.
Same rules as Binary Ionic/Stock but just name the polyatomic

40. Rally Table
NaF
K2CO3
MgCl2
Be(OH)2

41. Practice Worksheet
Refer to “Naming Ionic Compounds Practice Worksheet”
Make Flash Cards: Polyatomic Ions

42. Start 11/5/12

43. Brain Teaser (11/5/12)
Write the formula and draw the Lewis Dot structure: Potassium and Phosphorus
Name or Write the formula of the following compounds:
SrS
Cu2S
Iron (II) oxide
Magnesium cyanide

44. Agenda (11/5) Brain Teaser Collect Progress Report
Grade Practice Ionic Bonding Quiz and WS
Questions?
Ionic Review Questions
Ionic Bonding Quiz
Notes: Covalent Bond
Homework
Study Ionic Compounds Worksheet

45. Compounds How do we distinguish between ionic and covalent compounds?
What do you notice?

46. Why do atoms form bonds? Covalent bond
Shared pair of electrons between two atoms.
Non-metal and Non-metal

47. Lewis Structures
Lewis Structures A representation of a molecule that shows
how the valence electrons are arranged among
the atoms in the molecule
* G. N. Lewis
Lewis Dot Examples

48. Why do atoms form bonds? Molecule Diatomic Molecules Super 7
A group of atoms united by a covalent bond
A few elements only exist as a pair of atoms never as a single lone atom
Cl2, I2, F2, Br2, O2, H2, N2

49. Round Table – Covalent Bonding
SiH4
NH41+
H2Se
HCl HF
*SO42-

50. Why do atoms form bonds? Characteristics of covalent bonds
Single Bonds
Ex. H2
Double Bonds
Ex. O2, H2CO
Triple Bonds
Ex. N2, C2H2
Can form multiple bonds satisfy the octet rule
Two atoms share exactly one pair of electrons.
Two pairs of electrons shared between two atoms.
Three pairs of electrons are shared between atoms

51. Properties of Covalent Bonds
Solids are usually soft
low melting points
low boiling points
Properties arise because molecules are not strongly held together
Usually found with nonmetals

52. Structural Formulas Why do atoms form bonds?
Specifies which atoms are bonded to each other
Distinguish the difference between substances with the same molecular formula

53. Structural Formulas Examples
See models of different types: Why do we have different types of models?

54. Structural Formulas A few Models NH3 CO2
How are the atoms connected? H2SO4

55. Lewis Structure for Super 7’s
Draw Lewis structures for super 7’s

56. Chemical Formulas
S8, O2, O3 - What formulas do we find for elements? Elements with different formulas are called allotropes.
How many atoms make a molecule? Is there any pattern?
xenon oxygen phosphorus sulfur ozone

57. Brain Teaser
Write the Lewis structure for each of the following simple molecules.
H2S
C2H4
SiF4

58. Shapes Lab Work with a partner
Draw the Lewis Dot Diagrams for each of the compounds
Build each of the compounds using the model kits.
Sketch the shape of the model
Remember all the holes (bonding sites) of each atom must be filled in order for it to satisfy the octet rule.

59. Shapes of Molecules VSEPR Theory Valence Shell Electron Pair Repulsion
System for predicting molecular shape based on the idea that pairs of electrons orient themselves as far apart as possible.

60. Shapes of Molecules How to use VSEPR theory Examples
Total Electron Pairs
# of Shared and unshared pairs
Shared Electron Pairs
# of Pairs involved in covalent bonding
Unshared electron Pairs
# of Lone pairs of electron
Shape or Geometry
Linear, bent, trigonal planar, tetrahedral
Examples
HBr
H2O
PH3

61. Shapes of Molecules What do we do with multiple bonds?
Count the sides of the central atom that have bonds on them
Examples N2
HCN
H2CO

62. Practice
Shapes of molecules

63. THE PASS IT GAME!! You will have one paper for each row.
Your job is to do one section and then pass it to the next person.
There are three sections: Electron dot, molecular drawing and VSEPR name & angle
Once the last person is done raise your hand and get a stamp if all is correct.
1st team will get a prize for each Pass it game!

64. CCl4

65. SeO3

66. BeF2

67. Polarity of Molecules Electronegativity Polar Covalent Bonds
Polar Molecule
Ex. H2O
Ability to attract electrons
Difference in electronegativity tells us who wants the electrons more.
Atoms do not share electrons evenly.
Atoms with greater electronegativity have a slight negative charge.
A molecule is polar if the charge is not evenly distributed

68. Polarity of Molecules If the 2 atoms have similar electronegativities.
What would make a Non-Polar Covalent Bond?
Examples F2
PH3
If the 2 atoms have similar electronegativities.
The atoms involved exert similar pull on the electrons.

69. Bond Types and Elctronegativity
Electronegativity Difference
Bond Type
< 0.4
Non- polar covalent
Between 0.5 and 1.9
Polar covalent
> 2.0
Ionic

70. Polarity of Molecules Other side of shapes
Draw each molecule in its correct VSEPR shape.

71. Properties Ionic vs. Covalent

72. Rally Table - Types of chemical bonds