1. Chapter Five Ionic & Covalent Compounds

2. Section 5.1 Compounds

3. Revisiting Compounds
Compound is composed of two or more elements combined in a specific ratio and held together by chemical bonds.
Cannot be broken down by physical means.

4. Section 5.2 Lewis Dot Symbols

5. Why do atoms bond? Want to achieve stable electron configurations
Noble Gas configurations
Valence electrons (outer electrons) are involved in bonding
# of v.e. come from the group number
Lewis Dot Symbols (or diagrams) show this

6. Lewis Dot Symbols/Diagrams
Draw the element symbol
Represent v.e. with dots around the symbol
4 sides of the element symbol
Start on top of symbol
No more than 2 dots per side (max 8 for element)
Do not double up electrons until each side has 1 v.e.
Can be drawn for atoms or ions

7. Group Quiz #1 X Draw the Lewis Dot Diagrams for the following:
Silicon atom (Si)
Bromide ion (Br-)
What group of the periodic table does element X belong if its Lewis Dot Symbol was X

8. Section 5.3 Ionic Compounds & Bonding

9. Ionic Compounds
Contain cations (positive ions) and anions (negative ions)
Bonded together through ionic bonding: electrostatic attraction between oppositely charged particles
Results from a transfer of electrons
Ions cancel each other out producing a neutral compound

10. Transfer of Electrons Na Cl
With ionic bonds, electrons are TRANSFERRED
Na Cl - +

11. Ionic Compounds & Structure
A chemical formula or just formula indicates the ratio of elements in a compound
NaCl Li2O K3N Al2O3
Held together by a lattice work
Individual compounds in a lattice work are called
formula units.

12. Lattice Energy
Lattice Energy is amount of energy required to convert a mole of an ionic solid to its constituent ions in the gas phase
Ex: NaCl has a lattice energy of 788 kJ/mol
It takes 788 kJ of energy to convert 1 mole of NaCl to 1 mole of Na+(g) and Cl-(g)
The higher the lattice energy, the more stable the ionic compound is

13. Lattice Energy Examples

14. Factors that Affect Lattice Energy
Ionic Radius (distance between nuclei)
Magnitude of Charges
1) Ionic Radius
When distance between nuclei increases, attraction decreases, therefore weakening lattice energy

15. Factors that Affect Lattice Energy
Ionic Radius (distance between nuclei)

16. Factors that Affect Lattice Energy
2) Magnitude of Charges
When distances are similar between nuclei, we must look at charges
The higher the charge, the stronger the attraction, the stronger the lattice energy

17. Factors that Affect Lattice Energy
2) Magnitude of Charges

18. Section 5.4 Naming Ions & Ionic Compounds

19. Naming monatomic ions Also known as nomenclature Naming monatomic ions
Groups 1A, 2A, and 3A elements have charges equal to their group # (recall e- configs)
Most anions from elements in groups 4A-7A have charges equal to their group # is 8
Ex: Oxygen Group 6 – 8 = -2

20. Charges you will need to know
P. 123

21. Naming monatomic ions Cations:
Named simply by putting the word ion to the name of the element
Ex: K+ is the potassium ion, Al3+ is the aluminum ion
Certain metals form more than one charge
Ex: Fe2+ and Fe3+
Older system: Fe2+  Ferrous ion; Fe3+  Ferric ion
Newer system: Fe2+  iron (II) ion; Fe3+  iron (III) ion

22. Naming monatomic ions Anions
Named by changing the element’s ending to –ide and adding the word ion
Ex: Br- is the bromide ion; O2- is the oxide ion

23. Writing Formulas Cation and anion charges must equal ZERO
Use the criss-cross method to write formulas showing lowest whole number ratio
Ex: Potassium Bromide, Zinc Iodide, Aluminum Oxide

24. Naming Ionic Compounds
Most ionic compounds are binary (only 2 elements: metal and nonmetal—in other words, cation & anion)
Ionic compounds are named by using the cation name followed by the anion name, eliminating the words “ion”
Ex: NaBr  Sodium Bromide
CaF2 Calcium Fluoride
Al2N3  Aluminum Nitride

25. Naming Ionic Compounds
What about ionic compounds with transition metals???
Use “reverse criss-cross” to determine original charge of cation (be sure anion has correct charge)
Ex: FeCl2
Cr2S3
MnO

26. Group Quiz #2 If given the formula, write the name
If given the name, write the formula
Ag+ sodium ion
N3- zinc bromide
K2O Strontium Carbide

27. Section 5.5 Covalent Bonding & Molecules

28. F F Covalent Bonding Bonding typically between two nonmetals
Electrons are shared; both atoms “feel” like they have a noble gas configuration F F

29. Molecules
A neutral combination of at least 2 atoms in a specific arrangement held together by a chemical bond/force
Can be an element (H2) or a compound (H2O)

30. Diatomic Molecules Molecules with only 2 atoms
Homonuclear: two of the same element
H2, N2, O2, F2, Cl2, Br2, I2
HOFBrINCl
Heteronuclear: two different elements
CO, HCl, etc.

31. More with Molecules
Allotrope: Elements with different distinct forms (ex: Carbon graphite & diamonds)

32. Different ways to represent molecules

33. Section 5.6 Naming Molecular Compounds

34. Traditional Naming

35. Traditional Naming Name the first element as is
Add the appropriate prefix to signify # of atoms
Exclude mono for first element if there’s only one
Name the second element with –ide ending
Ex: N2P5 CS SO3

36. Writing the formulas Sulfur Tetrafluoride Tetraphosphorus Decasulfide
Tribromine Heptoxide

37. Exceptions Ex: SnCl4 and PbCl4
Can be named using ionic or covalent naming
Tin (IV) Chloride or Tin Tetrachloride; Lead (IV) Chloride or Lead Tetrachloride

38. Exceptions: Hydrogen Compounds
B2H6 Diborane
SiH4 Silane
NH3 Ammonia
PH3 Phosphine
H2O Water
H2S Hydrogen Sulfide
*Responsible for knowing the one’s in red

39. Exceptions: Binary Acids
Acids typically have hydrogen at the beginning
When dissolved in water, they typically produce hydrogen ions (H+)
HCl in gas form is hydrogen chloride
HCl dissolved in water is hydrochloric acid

40. Binary Acids How to name binary acids: Change “hydrogen” into “hydro-”
Take the root of the second element and add “-ic” to the ending.
End with acid
Ex: HBr(aq)

41. Name/Write these acids
Hydrofluoric acid
H3N(aq)
Hydrosulfuric acid
H3P(aq)

42. Group Quiz #3 Name/Write the following: SF6 P2I4 Diboron Heptoxide
Hydroiodic acid
H2Se(aq)

43. Section 5.7 Covalent Bonding in Ionic Species

44. Compounds with Polyatomic Ions
Polyatomic ions: ions that contain multiple atoms/elements (held together by covalent bonding)
Act as a group; can be treated as one
Name these compounds using
the same rules as we did for ionic
You must know table 5.10 in your
text book!

45. List of Polyatomic Ions from Text
You are responsible for knowing the name, the formula, and the charge for each polyatomic ion in table 5.10 (this is a SHORTENED list!)

46. Writing Formulas Ammonium Chloride Cobalt (II) Nitrate Try These
Calcium Phosphate
Manganese (III) Carbonate

47. Naming Formulas
Name the following compounds:
Fe2(SO4)
Al(OH)3
NH4NO2

48. Oxoacids Acids that contain oxoanions (polyatomic ions with oxygen)
Ex: NO3- makes the oxoacid HNO3(aq)
Ex: SO42- makes the oxoacid H2SO4(aq)
Continue adding hydrogen (+1) to the beginning of the oxoanion until the net charge is ZERO
Just like ionic rules

49. Naming Oxoacids Do NOT start with hydro-
START with the root of the polyatomic ion
Add the appropriate suffix
If the polyatomic ends in –ate, change to –ic
If the polyatomic ends in –ite, change to –ous
4) Add the word “acid
Example: H2CrO4 HNO2

50. Monoprotic vs. Polyprotic Acids
Monoprotic only has 1 ionizable hydrogen
HNO3, HCl, HC2H3O2
Polyprotic has more than 1 ionizable hydrogen
H2S, H3PO4
Ionization will happen in steps

51. Hydrates
Compounds with specific number of water molecules within its solid structure
Use greek prefixes to name water part
CuSO4 * 5H2O
Anhydrous salt is the compound w/o water
Has distinct different properties than its hydrate form

52. Group Quiz #4 Name/Write the following Sulfurous Acid
Iron (II) Acetate
NaOH
H2CO3(aq)
Strontium Nitrate Tetrahydrate

53. Section 5.8 Molecular and Formula Masses

54. Review! Determine the molecular mass of the following compounds:
Propane, C3H8
Lithium Hydroxide, LiOH

55. Section 5.9 Percent Composition of Compounds

56. Percent Composition Percent by mass of every element in a compound
Divide the mass of element by the mass of the entire compound
Ex: What is the percent composition of H2O?

57. Section 5.10 Molar Mass

58. Review!

59. Empirical Formulas vs. Molecular Formulas
Molecular Formulas: The TRUE formula for a compound
Shows exactly how many of each element is in a compound via subscripts
Ex: C6H12O6, H2O
Empirical Formulas: The lowest WHOLE number ratio of elements in a compound
May or may not be the true formula
Ex: CH2O, H2O

60. Figuring out an empirical and molecular formula from percentages
Ex: An unknown compound was found to have a percent composition as follows:
47.0 % potassium, 14.5 % carbon, and 38.5 % oxygen. What is its empirical formula?
If the true molar mass of the compound is g/mol, what is its molecular formula?

61. Another Example
Nitrogen and oxygen form an extensive series of oxides with the general formula NxOy. One of them is a blue solid that comes apart, reversibly, in the gas phase. It contains 36.84% N. What is the empirical formula of this oxide?

62. Group Quiz #5 Write the empirical formula for the following compounds.
C8H18
C2H6O2
A compound with an empirical formula of C4H4O and a molar mass of 136 grams per mole. What is the molecular formula of this compound?