1. Modern Chemistry Chapter 7 Chemical Formulas & Chemical Compounds
A chemical formula indicates the kind and relative number of atoms in a chemical compound.
C8H18 (octane) has 8 carbon and 18 hydrogen atoms.

2. Forming Ionic Compounds
Compounds that have the elements held together by ionic bonds are called ionic compounds.
For an ionic compound to exist, the algebraic sum of the positive and the negative charges of the ions MUST = 0.
For instance, when a calcium atom becomes an ion, it has an overall 2+ charge which must be neutralized by ion(s) that have a 2- charge.
IF a Ca2+ cation forms an ionic bond with an O2- anion, the resulting compound will be neutral and the formula would be CaO.
However, if the Ca2+ bonds with a F- anion, it would require two F- ions to neutralize the Ca2+  CaF2

3. Calcium ( Ca2+ ) combines with oxygen ( O2- )  CaO : Ca2+ O2- Calcium (Ca2+ ) combines with fluorine (F1- )  CaF2: F1- Ca F1-

4. Binary Ionic Compounds
monatomic ions- ions formed from a single atom
IF the ion has a positive charge, use the name of the element
IF the ion has a negative charge, replace the ending of the element name with “ide”.

5. Binary Ionic Compounds
binary compound- a compound composed of two elements
Writing binary ionic compound formulas:
Write the symbols for the ions side by side with the cation being first.
IF the charges of the two ions do not add to zero, cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion so the algebraic sum of the ions equals zero.
Check the subscripts and make sure they are in the smallest whole number ratio possible.
e.g. aluminum oxide Al3+O  Al2O3

6. Naming Binary Ionic Compounds
nomenclature- a naming system
Naming ionic compounds:
Write the name of the cation in the formula.
Write the name of the anion in the formula.
Al2O3  aluminum oxide
Do practice problems #1 & 2 on page 223.

7. Problems- page 223 a- potassium (K+) & iodide (I-)  KI
b- magnesium (Mg2+) & chloride (Cl-) 
MgCl2
c- sodium (Na+) & sulfide (S2-) 
Na2S
d- aluminum (Al3+) & sulfide (S2-) 
Al2S3
e- aluminum (Al3+) & nitride (N3-) 
AlN

8. #2 a) AgCl 
silver chloride
b) ZnO 
zinc oxide
c) CaBr2 
calcium bromide
d) SrF2 
strontium fluoride
e) BaO 
barium oxide
f) CaCl2 
calcium chloride

9. Chapter 7
Common Monatomic Ions

10. Chapter 7
Common Monatomic Ions

11. Stock System of Nomenclature
Some metallic elements that form cations such as chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, and tin can form cations of more than one charge. (See ion chart)
For cations that can have multiple ionic charges, place a Roman numeral in parentheses that is equal to the ionic charge after the name of the metal.
Cu1+  copper (I) Fe2+  iron (II)
Cu2+  copper (II) Fe3+  iron (III)

12. Naming Binary Ionic Compounds, continued
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Ionic Compounds, continued
The Stock System of Nomenclature, continued
Sample Problem B
Write the formula and give the name for the compound formed by the ions Cr3+ and F–.

13. Cr3+ F− Cr3+ F– Chapter 7 Naming Binary Ionic Compounds, continued
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Ionic Compounds, continued
The Stock System of Nomenclature, continued
Sample Problem B Solution
Write the symbols for the ions side by side. Write the cation first.
Cr3+ F−
Cross over the charges to give subscripts.
Cr3+ F–
1 3

14. Naming Binary Ionic Compounds, continued
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Ionic Compounds, continued
The Stock System of Nomenclature, continued
Sample Problem B Solution, continued
Chromium forms more than one ion, so the name of the 3+ chromium ion must be followed by a Roman numeral indicating its charge.
The compound’s name is
chromium(III) fluoride.

15. Using the Stock System Write the formula of the ionic compound.
Use the charge of the anion to determine the charge of the cation.
Write the name of the cation with the charge followed by the name of the anion.
CuCl  copper (I) chloride
CuCl2  copper (II) chloride
Do practice problems #1 & 2 on page 225.

16. Practice- page 225 CuBr2  copper (II) bromide b) Fe 2+ & O2- 
#1 a) Cu2+ & Br- 
CuBr2  copper (II) bromide
b) Fe 2+ & O2- 
FeO  iron (II) oxide
c) Pb 2+ & Cl- 
PbCl2  lead (II) chloride
d) Hg 2+ & S2- 
HgS  mercury (II )sulfide
e) Sn 2+ & F- 
SnF2  tin (II) fluoride
f) Fe 3+ & O2- 
Fe2O3  iron (III) oxide

17. Practice- page 225
#2 a) CuO 
copper II oxide
b) CoF3 
cobalt III fluoride
c) SnI4 
tin IV iodide
d) FeS 
iron II sulfide

18. Polyatomic Ions
polyatomic ion- a group of covalently bonded atoms with a charge
oxyanion- a negatively charged polyatomic ion that contains oxygen

19. NO NO Chapter 7 Naming Binary Ionic Compounds, continued
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Ionic Compounds, continued
Compounds Containing Polyatomic Ions
Many common polyatomic ions are oxyanions— polyatomic ions that contain oxygen.
Some elements can combine with oxygen to form more than one type of oxyanion.
example: nitrogen can form NO or NO .
3 2
The name of the ion with the greater number of oxygen atoms ends in -ate. The name of the ion with the smaller number of oxygen atoms ends in -ite.
NO NO 3
nitrate 2
nitrite

20. Naming Binary Ionic Compounds, continued
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Ionic Compounds, continued
Compounds Containing Polyatomic Ions, continued
Some elements can form more than two types of oxyanions.
example: chlorine can form ClO, ClO , ClO or ClO .
2 3 4
In this case, an anion that has one fewer oxygen atom than the -ite anion has is given the prefix hypo-.
An anion that has one more oxygen atom than the -ate anion has is given the prefix per-.
ClO
hypochlorite
ClO
ClO
ClO 2
chlorite 3
chlorate 4
perchlorate

21. Chapter 7
Polyatomic Ions

22. Naming Binary Ionic Compounds, continued
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Ionic Compounds, continued
Compounds Containing Polyatomic Ions, continued
Sample Problem C
Write the formula for tin(IV) sulfate.

23. Sn4+ SO2– Sn4+ Chapter 7 Naming Binary Ionic Compounds, continued
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Ionic Compounds, continued
Compounds Containing Polyatomic Ions, continued
Cross over the charges to give subscripts. Add parentheses around the polyatomic ion if necessary.
Sn4+ SO2– 4
Cross over the charges to give subscripts. Add parentheses around the polyatomic ion if necessary.
Sn4+
(SO )2– 2
4 4

24. Naming Binary Ionic Compounds, continued
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Ionic Compounds, continued
Compounds Containing Polyatomic Ions, continued
Sample Problem C Solution, continued
The total positive charge is 2 × 4+ = 8+.
The total negative charge is 4 × 2− = 8−.
The largest common factor of the subscripts is 2, so the smallest whole-number ratio of ions in the compound is 1:2.
Sn(SO4)2.
The correct formula is therefore

25. Ionic Compounds & Polyatomic Ions
Writing and naming strategies are the same for ionic compounds with polyatomic ions. However, if more than one polyatomic ion is needed in the formula, the formula of the polyatomic ion is placed in parentheses and a subscript is used outside the parenthesis to show how many of the polyatomic ions are needed.
e.g iron (II) nitrate  Fe(NO3)2
Do practice problems #1 & 2 on page 227.

26. Practice Problems #1 page 227
a- sodium iodide
NaI
b- calcium chloride
CaCl2
c- potassium sulfide
K2S
d- lithium nitrate
LiNO3

27. e- copper (II) sulfate
CuSO4
f- sodium carbonate
Na2CO3
g- calcium nitrite
Ca(NO2)2
h- potassium perchlorate KClO4

28. 2a- Ag2O
silver oxide
b- Ca(OH)2
calcium hydroxide
c- KClO3
potassium chlorate
d- NH4OH
ammonium hydroxide
e- Fe2(CrO4)3
iron (III) chromate
f- KClO
potassium hypochlorite

29. Practice Do the following formulas match the names given?
IF they do not match, provide the CORRECT name or formula.
CuSO4  copper I sulfate
Fe2(SO4)3  iron III sulfate
FeSO4  iron II sulfate
copper I nitrate  CuNO3
copper II nitrate  Cu2NO3

30. Practice CuSO4  copper I sulfate NO [copperII]
Do the following formulas match the names given?
CuSO4  copper I sulfate
NO [copperII]
Fe2(SO4)3  iron III sulfate
YES
FeSO4  iron II sulfate
copper I nitrate  CuNO3
copper II nitrate  Cu2NO3
NO [Cu(NO3)2]

31. Ionic Compound Nomenclature
Name the following compounds:
MgBr2
CuO
Cu2O
FeSO4
Fe2(SO4)3
CaSO4
Cu2SO4
CuSO4
FePO4
Fe3(PO4)2

32. Ionic Compound Nomenclature
Name the following compounds:
MgBr2
magnesium bromide
CuO
copper II oxide
Cu2O
copper I oxide
FeSO4
iron II sulfate
Fe2(SO4)3
iron III sulfate

33. CaSO4
calcium sulfate
Cu2SO4
copper I sulfate
CuSO4
copper II sulfate
FePO4
iron III phosphate
Fe3(PO4)2
iron II phosphate

34. Ionic Compound Nomenclature
Write the formulas of the following ionic compounds:
aluminum nitrate
aluminum nitride
magnesium phosphate
magnesium bromide
copper I sulfate
copper II sulfate
iron II nitrate
iron III fluoride
calcium hydroxide
calcium phosphate

35. aluminum nitrate Al 3+ NO3 1- Al(NO3)3 aluminum nitride Al 3+ N 3- AlN magnesium phosphate Mg 2+ PO4 3- Mg3(PO4)2

36. magnesium bromide Mg 2+ Br 1- MgBr2 copper I sulfate Cu 1+ SO4 2- Cu2SO4 copper II sulfate Cu 2+ SO4 2- CuSO4 iron II nitrate Fe 2+ NO3 1- Fe(NO3)2

37. iron III fluoride Fe 3+ F 1- FeF3 calcium hydroxide Ca 2+ OH 1- Ca(OH)2 calcium phosphate Ca 2+ PO4 3- Ca3(PO4)2

38. Naming Binary Molecular Compounds
Section 1 Chemical Names and Formulas
Chapter 7
Naming Binary Molecular Compounds
Unlike ionic compounds, molecular compounds are composed of individual covalently bonded units, or molecules.
As with ionic compounds, there is also a Stock system for naming molecular compounds.
The old system of naming molecular compounds is based on the use of prefixes.
examples:
CCl4 — carbon tetrachloride (tetra- = 4) CO — carbon monoxide (mon- = 1) CO2 — carbon dioxide (di- = 2)

39. Naming of Binary Molecular Compounds From Formulas
Write the name of the first element in the formula.
Write the name of the second element using the suffix “ide”.
Use numerical prefixes to show the number of atoms of each element.
e.g. P2O5  diphosphorus pentoxide
1 = mono 6 = hexa
2 = di 7 = hepta
3 = tri 8 = octa
4 = tetra 9 = nona
5 = penta = deca

40. Binary Molecular Compounds
P4O10  tetra + phosphorus & dec + oxide
tetraphosphorus decoxide
CO  carbon & mon + oxide
carbon monoxide
CO2  carbon & di + oxide
carbon dioxide

41. Formulas for Molecular Compounds
The element with the smaller group number is usually given first.
If both elements are in the same group, the element with the larger period number is given first. This element is given a prefix ONLY if it contributes more than one atom to the molecule of the compound.
The second element is named by combining a prefix for the number of atoms of the element in the compound, the root of the name of the element, and the suffix “ide”.
The “o” or the “a” at the end of a prefix is usually dropped when the word following the prefix begins with another vowel.

42. Writing Molecular Formulas
Write the formula of the first element in the compound name followed by the numerical subscript that shows how many there are (if there is no numerical prefix, there is one atom of the element).
Write the formula of the second element in the compound name followed by a subscript that shows how many atoms of the element are designated by the numerical prefix in the name.
carbon dioxide  CO2
Do practice problems #1 & 2 on page 229.

43. Practice Problems #1 & 2 page 229
1- a- SO3
sulfur trioxide
b- ICl3
iodine trichloride
c- PBr5
phosphorus pentabromide
2- a- carbon tetraiodide
CI4
b- phosphorus trichloride
PCl3
c- dinitrogen trioxide
N2O3

44. Molecular Compound Nomenclature
Name the following molecular compounds.
N2O5
SO2
P4O10 CO
CO2
SiO2
H2O2
CF4
PBr3
SF2

45. Name the following molecular compounds.
N2O5 dinitrogen pentoxide
SO2 sulfur dioxide
P4O10 tetraphosphorus decoxide
CO carbon monoxide
CO2 carbon dioxide
SiO2 silicon dioxide
H2O2 dihydrogen dioxide
CF4 carbon tetrafluoride
PBr3 phosphorus tribromide
SF2 sulfur difluoride

46. Molecular Compound Nomenclature
Write the formula for the following compounds.
carbon tetraiodide
trinitrogen heptoxide
triphosphorus hexasulfide
oxygen dichloride
disilicon triphosphide
tetranitrogen heptoxide
carbon disulfide
dihydrogen monosulfide
trihydrogen monophosphide
silicon disulfide

47. Molecular Compound Nomenclature
Write the formula for the following compounds.
carbon tetraiodide CI4
trinitrogen heptoxide N3O7
triphosphorus hexasulfide P3S6
oxygen dichloride OCl2
disilicon triphosphide Si2P3
tetranitrogen heptoxide N4O7
carbon disulfide CS2
dihydrogen monosulfide H2S
trihydrogen monophosphide H3P
silicon disulfide SiS2

48. Section Review Problem #2 page 231
2- a- aluminum + bromine 
AlBr3
b- sodium + oxygen 
Na2O
c- magnesium + iodine 
MgI2
d- lead (II) + oxygen 
PbO
e- tin (II) + iodine  SnI2
f- iron (III) + sulfur  Fe2S3
g- copper (II) + nitrate  Cu(NO3)2
h- ammonium + sulfate  (NH4)2SO4

49. Section Review Problem #3 page 231
a- NaI 
sodium iodide
b- MgS 
magnesium sulfide
c- CaO 
calcium oxide
d- K2S 
potassium sulfide
e- CuBr  copper (I) bromide
f- FeCl2  iron (II) chloride

50. Section Review Problem #4 (a-e) page 231
a- sodium hydroxide 
NaOH
b- lead (II) nitrate 
Pb(NO3)2
c- iron (II) sulfate 
FeSO4
d- diphosphorus trioxide 
P2O3
e- carbon diselenide 
CSe2