Slide 1 : Chapter 5
Molecules and
Compounds
Molecules and Compounds : Tro's "Introductory Chemistry", Chapter 5 2 Molecules and Compounds Salt
Sodium—shiny, reactive, poisonous.
Chlorine—pale yellow gas, reactive, poisonous.
Sodium chloride—table salt.
Sugar
Carbon—pencil or diamonds.
Hydrogen—flammable gas.
Oxygen—a gas in air.
Combine to form white crystalline sugar.
Law of Constant Composition : Tro's "Introductory Chemistry", Chapter 5 3 Law of Constant Composition All pure substances have constant composition.
All samples of a pure substance contain the same elements in the same percentages (ratios).
Mixtures have variable composition.
Compounds Display Constant Composition : Tro's "Introductory Chemistry", Chapter 5 4 Compounds Display Constant Composition If we decompose water by electrolysis, we find 16.0 grams of oxygen to every 2.00 grams of hydrogen.
Water has a constant mass ratio of oxygen to hydrogen of 8.0.
Example 5.1—Show that Two Samples of Carbon Dioxide Are Consistent with the Law of Constant Composition. : Example 5.1—Show that Two Samples of Carbon Dioxide Are Consistent with the Law of Constant Composition. Since both samples have the same proportion of elements, carbon dioxide shows constant composition. Compare: Solution: composition = mass O : mass C Solution Map:
Relationships: Sample 1: 4.8 g O, 1.8 g C;
Sample 2: 17.1 g O, 6.4 g C
proportion O:C Given:
Find:
Practice—Show that Hematite Has Constant Composition if a 10.0 g Sample Has 7.2 g Fe and the Rest Is Oxygen; and a Second Sample Has 18.1 g Fe and 6.91 g O. : Tro's "Introductory Chemistry", Chapter 5 6 Practice—Show that Hematite Has Constant Composition if a 10.0 g Sample Has 7.2 g Fe and the Rest Is Oxygen; and a Second Sample Has 18.1 g Fe and 6.91 g O.
Example 5.1—Show that Two Samples of Hematite Are Consistent with the Law of Constant Composition. : Example 5.1—Show that Two Samples of Hematite Are Consistent with the Law of Constant Composition. Since both samples have the same proportion of elements, hematite shows constant composition. Compare: Solution: composition = mass Fe : mass O Solution Map:
Relationships: Sample 1: 7.2 g Fe, (10.0-7.2) = 2.8 g O;
Sample 2: 18.1 g Fe, 6.91 g O
proportion Fe:O Given:
Find:
Why Do Compounds ShowConstant Composition? : Tro's "Introductory Chemistry", Chapter 5 8 Why Do Compounds ShowConstant Composition? The smallest piece of a compound is called a molecule.
If you have a pure substance, then every molecule will have the same number and type of atoms.
Therefore, your compound have the same predictable properties (physical & chemical).
Formulas Describe Compounds : Tro's "Introductory Chemistry", Chapter 5 9 Formulas Describe Compounds Elements are represented by a letter symbol.
A pure compound is composed of atoms of two or more elements.
The number of each element is written to the right of the element as a subscript.
If there is only one atom, the 1 subscript is not written.
Polyatomic groups are placed in parentheses.
If more than one.
Formulas Describe Compounds, Continued : 10 Formulas Describe Compounds, Continued Water = H2O \ two atoms of hydrogen and 1 atom of oxygen Table salt = NaCl, one sodium and one chlorine atom: notice that pure substances have consistent structures, these pure substance will also have consistent physical and chemical properties.
Order of Elements in a Formula : Tro's "Introductory Chemistry", Chapter 5 11 Order of Elements in a Formula Metals are written first.
NaCl
Nonmetals are written in order from Table 5.1.
CO2
There are occasional exceptions for historical or informational reasons.
H2O, but NaOH .
Practice—Write Formulas for Each of the Following Compounds. : Tro's "Introductory Chemistry", Chapter 5 12 Practice—Write Formulas for Each of the Following Compounds. Hematite—Composed of four oxide ions for every three iron ions.
Acetone—Each molecule contains six hydrogen atoms, three carbon atoms, and one oxygen atom. Fe3O4 C3H6O
Molecules with Polyatomic Ions : Tro's "Introductory Chemistry", Chapter 5 13 Molecules with Polyatomic Ions Mg(NO3)2
Compound called
magnesium nitrate. CaSO4
Compound called
calcium sulfate.
Molecules with Polyatomic Ions, Continued : 14 Molecules with Polyatomic Ions, Continued Mg(NO3)2
Compound called
magnesium nitrate. CaSO4
Compound called
calcium sulfate.
Practice—Determine the Total Number of Atoms or Ions in One Formula Unit of Each of the Following. : Tro's "Introductory Chemistry", Chapter 5 15 Practice—Determine the Total Number of Atoms or Ions in One Formula Unit of Each of the Following. Mg(C2H3O2)2
(Hg2)3(PO4)2 1 Mg + 4 C + 6 H + 4 O = 15 6 Hg + 2 P + 8 O = 16
Classifying Materials : 16 Classifying Materials Atomic elements = are single atoms.
Molecular elements = multi-atom molecules.
Molecular compounds = molecules made of only nonmetals.
Ionic compounds = Compounds made of cations and anions.
More about Molecular Elements : 17 More about Molecular Elements Certain elements occur as diatomic molecules.
7 diatomic elements—The Rule of 7s
Find the element with atomic number 7, N.
Make a figure 7 by going over to Group 7A, then down.
The seventh element is H2. H2 Cl2 Br2 I2 7 7A N2 O2 F2
Molecular Compounds : Molecular Compounds Two or more nonmetals.
Smallest unit is a molecule.
Ionic Compounds : Tro's "Introductory Chemistry", Chapter 5 19 Ionic Compounds Metals + nonmetals.
No individual molecule units, instead have a 3-dimensional array of cations and anions made of formula units.
Molecular View of Elements and Compounds : 20 Molecular View of Elements and Compounds
Classify Each of the Following as Either an Atomic Element, Molecular Element, Molecular Compound, or Ionic Compound, Continued. : Tro's "Introductory Chemistry", Chapter 5 21 Classify Each of the Following as Either an Atomic Element, Molecular Element, Molecular Compound, or Ionic Compound, Continued. Aluminum, Al = Atomic element.
Aluminum chloride, AlCl3 = Ionic compound.
Chlorine, Cl2 = Molecular element.
Acetone, C3H6O = Molecular compound.
Carbon monoxide, CO = Molecular compound.
Cobalt, Co = Atomic element.
Ionic Compounds : Tro's "Introductory Chemistry", Chapter 5 22 Ionic Compounds Ionic compounds are made of ions called cations and anions.
Cations = + charged ions; anions = − charged ions.
The sum of the + charges of the cations must equal the sum of the − charges of the anions.
If Na+ is combined with S2-, you will need 2 Na+ ions for every S2- ion to balance the charges, therefore the formula must be Na2S.
Writing Formulas for Ionic Compounds : Tro's "Introductory Chemistry", Chapter 5 23 Writing Formulas for Ionic Compounds Write the symbol for the metal cation and its charge.
Write the symbol for the nonmetal anion and its charge.
Charge (without sign) becomes subscript for the other ion.
Reduce subscripts to smallest whole-number ratio.
Check that the sum of the charges of the cation cancels the sum of the anions.
Write the Formula of a Compound Made from Aluminum Ions and Oxide Ions. : Tro's "Introductory Chemistry", Chapter 5 24 Write the Formula of a Compound Made from Aluminum Ions and Oxide Ions. Write the symbol for the metal cation and its charge.
Write the symbol for the nonmetal anion and its charge.
Charge (without sign) becomes subscript for the other ion.
Reduce subscripts to smallest whole-number ratio.
Check that the total charge of the cations cancels the total charge of the anions. Al+3 column 3A O2- column 6A Al+3 O2- Al2O3 Al = (2)∙(+3) = +6
O = (3)∙(-2) = -6
Practice—What Are the Formulas for Compounds Made from the Following Ions? : Tro's "Introductory Chemistry", Chapter 5 25 Practice—What Are the Formulas for Compounds Made from the Following Ions? Potassium ion with a nitride ion. K+ with N3- K3N
Calcium ion with a bromide ion. Ca+2 with Br- CaBr2
Aluminum ion with a sulfide ion. Al+3 with S2- Al2S3
Practice—What Are the Formulas for Compounds Made from the Following Ions? : Tro's "Introductory Chemistry", Chapter 5 26 Practice—What Are the Formulas for Compounds Made from the Following Ions? Copper(II) ion with a nitride ion.
Iron(III) ion with a bromide ion.
Practice─Name the Following Compounds. : Tro's "Introductory Chemistry", Chapter 5 27 Practice─Name the Following Compounds. Ti4+ Cl-
Pb2+ Br-
Fe3+ S2-
Formula Mass : Tro's "Introductory Chemistry", Chapter 5 28 Formula Mass The mass of an individual molecule or formula unit.
Also known as molecular mass or molecular weight.
Sum of the masses of the atoms in a single molecule or formula unit.
Whole = Sum of the parts.
Mass of 1 molecule of H2O
= 2(1.01 amu H) + 16.00 amu O = 18.02 amu.
Practice—Calculate the Formula Mass of : Tro's "Introductory Chemistry", Chapter 5 29 Practice—Calculate the Formula Mass of Al2(SO4)3
Cr(HCO3)2
End: if Lab is on nomenclature : End: if Lab is on nomenclature Tro's "Introductory Chemistry", Chapter 5 30
Formula-to-NameStep 1 : Tro's "Introductory Chemistry", Chapter 5 31 Formula-to-NameStep 1 Is the compound one of the exceptions to the rules?
Common Names—Exceptions : Tro's "Introductory Chemistry", Chapter 5 32 Common Names—Exceptions H2O = Water, steam, ice.
NH3 = Ammonia.
CH4 = Methane.
NaCl = Table salt.
C12H22O11 = Table sugar.
Formula-to-NameStep 2 : Tro's "Introductory Chemistry", Chapter 5 33 Formula-to-NameStep 2 What major class of compound is it?
Ionic or Molecular?
Major Classes : Tro's "Introductory Chemistry", Chapter 5 34 Major Classes Ionic compounds.
Metal + nonmetal(s).
Metal first in formula.
Binary ionic or compounds with polyatomic ions.
Molecular compounds.
2 or more nonmetals.
Binary molecular (or binary covalent).
2 nonmetals.
Acids—Formula starts with H.
Though acids are molecular, they behave as ionic when dissolved in water.
May be binary or oxyacid.
Formula-to-NameStep 3 : Tro's "Introductory Chemistry", Chapter 5 35 Formula-to-NameStep 3 What major subclass of compound is it?
Binary Ionic, Ionic with Polyatomic Ions,
Binary Molecular,
Binary Acid, or Oxyacid?
Classifying Compounds : Tro's "Introductory Chemistry", Chapter 5 36 Classifying Compounds Compounds containing a metal and a nonmetal = Binary ionic.
Type I and II.
Compounds containing a polyatomic ion = Ionic with polyatomic ion.
Compounds containing two nonmetals = Binary molecular compounds.
Compounds containing H and a nonmetal = Binary acids.
Compounds containing H and a polyatomic ion = Oxyacids.
Formula-to-NameStep 4 : Tro's "Introductory Chemistry", Chapter 5 37 Formula-to-NameStep 4 Apply rules for the class and subclass.
Formula-to-NameRules for Ionic : Tro's "Introductory Chemistry", Chapter 5 38 Formula-to-NameRules for Ionic Made of cation and anion.
Name by simply naming the ions.
If cation is:
Type I metal = Metal name.
Type II metal = Metal name (charge).
Polyatomic ion = Name of polyatomic ion.
If anion is:
Nonmetal = Stem of nonmetal name + -ide.
Polyatomic ion = Name of polyatomic ion.
Monatomic Nonmetal Anion : Tro's "Introductory Chemistry", Chapter 5 39 Monatomic Nonmetal Anion Determine the charge from position on the periodic table.
To name anion, change ending on the element name to –ide.
Metal Cations : Tro's "Introductory Chemistry", Chapter 5 40 Metal Cations Type I
Metals whose ions can only have one possible charge.
1A, 2A, (Al, Zn, Ag).
Determine charge by position on the periodic table.
1A = +, 2A = 2+, Al = 3+.
Some need to be memorized.
Zn = 2+, Ag = +.
Type II
Metals whose ions can have more than one possible charge.
Determine charge by charge on anion. How do you know a metal cation is Type II?
Determine if the Following Metals are Type I or Type II. If Type I, Determine the Charge on the Cation it Forms. : Tro's "Introductory Chemistry", Chapter 5 41 Determine if the Following Metals are Type I or Type II. If Type I, Determine the Charge on the Cation it Forms. Lithium, Li.
Copper, Cu.
Gallium, Ga.
Tin, Sn.
Strontium, Sr.
Determine if the Following Metals are Type I or Type II. If Type I, Determine the Charge on the Cation it Forms, Continued. : Tro's "Introductory Chemistry", Chapter 5 42 Determine if the Following Metals are Type I or Type II. If Type I, Determine the Charge on the Cation it Forms, Continued. Lithium, Li Type I 1+
Copper, Cu Type II
Gallium, Ga Type I 3+
Tin, Sn Type II
Strontium, Sr Type I 2+
Type I Binary Ionic Compounds : Tro's "Introductory Chemistry", Chapter 5 43 Type I Binary Ionic Compounds Contain metal cation + nonmetal anion.
Metal listed first in formula and name.
Name metal cation first, name nonmetal anion second.
Cation name is the metal name.
Nonmetal anion named by changing the ending on the nonmetal name to –ide.
Example—Naming Binary Ionic, Type I Metal, CsF : Tro's "Introductory Chemistry", Chapter 5 44 Example—Naming Binary Ionic, Type I Metal, CsF Is it one of the common exceptions?
H2O, NH3, CH4, NaCl, C12H22O11 = No!
Identify major class.
Cs is a metal because it is on the left side of the periodic table.
F is a nonmetal because it is on the right side of the periodic table.
Ionic.
Identify the subclass.
2 elements, Binary ionic.
Is the metal Type I or Type II?
Cs is in Group 1A, Type I.
Example—Naming Binary Ionic, Type I Metal, CsF, Continued : Tro's "Introductory Chemistry", Chapter 5 45 Example—Naming Binary Ionic, Type I Metal, CsF, Continued Identify cation and anion.
Cs = Cs+ because it is Group 1A.
F = F- because it is Group 7A.
Name the cation.
Cs+ = cesium.
Name the anion.
F- = fluoride.
Write the cation name first, then the anion name.
cesium fluoride.
Practice—Name the Following Compounds. : Tro's "Introductory Chemistry", Chapter 5 46 Practice—Name the Following Compounds. KCl
MgBr2
Al2S3
Practice—Name the Following Compounds, Continued. : Tro's "Introductory Chemistry", Chapter 5 47 Practice—Name the Following Compounds, Continued. KCl potassium chloride.
MgBr2 magnesium bromide.
Al2S3 aluminum sulfide.
Type II Binary Ionic Compounds : Tro's "Introductory Chemistry", Chapter 5 48 Type II Binary Ionic Compounds Contain metal cation + nonmetal anion.
Metal listed first in formula and name.
Name metal cation first, name nonmetal anion second.
Metal cation name is the metal name followed by a roman numeral in parentheses to indicate its charge.
Determine charge from anion charge.
Common Type II cations in Table 5.5.
Nonmetal anion named by changing the ending on the nonmetal name to –ide.
Determining the Charge on a Variable Charge Cation—Au2S3 : Tro's "Introductory Chemistry", Chapter 5 49 Determining the Charge on a Variable Charge Cation—Au2S3 Determine the charge on the anion.
Au2S3 - the anion is S, since it is in Group 6A, its charge is 2−.
Determine the total negative charge.
Since there are 3 S in the formula, the total negative charge is −6.
Determine the total positive charge.
Since the total negative charge is −6, the total positive charge is +6.
Divide by the number of cations.
Since there are 2 Au in the formula and the total positive charge is +6, each Au has a 3+ charge.
Example—Writing Formula for a Binary Ionic Compound Containing Variable Charge Metal, Manganese(IV) Sulfide : Tro's "Introductory Chemistry", Chapter 5 50 Example—Writing Formula for a Binary Ionic Compound Containing Variable Charge Metal, Manganese(IV) Sulfide Write the symbol for the cation and its charge.
Write the symbol for the anion and its charge.
Charge (without sign) becomes subscript for the other ion.
Reduce subscripts to smallest whole-number ratio.
Check that the total charge of the cations cancels the total charge of the anions. Mn+4 S2- Mn+4 S2- Mn2S4 Mn = (1)∙(+4) = +4
S = (2)∙(-2) = -4 MnS2
Practice—What Are the Formulas for Compounds Made from the Following Ions? : Tro's "Introductory Chemistry", Chapter 5 51 Practice—What Are the Formulas for Compounds Made from the Following Ions? Copper(II) ion with a nitride ion.
Iron(III) ion with a bromide ion.
Practice—What Are the Formulas for Compounds Made from the Following Ions?, Continued : Tro's "Introductory Chemistry", Chapter 5 52 Practice—What Are the Formulas for Compounds Made from the Following Ions?, Continued Cu2+ with N3- Cu3N2
Fe+3 with Br- FeBr3
Example—Naming Binary Ionic, Type II Metal,CuCl : Tro's "Introductory Chemistry", Chapter 5 53 Example—Naming Binary Ionic, Type II Metal,CuCl Is it one of the common exceptions?
H2O, NH3, CH4, NaCl, C12H22O11 = No!
Identify major class.
Cu is a metal because it is on the left side of the periodic table.
Cl is a nonmetal because it is on the right side of the periodic table.
Ionic.
Identify the subclass.
2 elements, Binary ionic.
Is the metal Type I or Type II?
Cu is not in Group 1A, 2A, or (Al, Zn, Ag) Type II.
Example—Naming Binary Ionic, Type II Metal, CuCl, Continued : Tro's "Introductory Chemistry", Chapter 5 54 Example—Naming Binary Ionic, Type II Metal, CuCl, Continued Identify cation and anion.
Cl = Cl− because it is Group 7A.
Cu = Cu+ to balance the charge.
Name the cation.
Cu+ = Copper(I).
Name the anion.
Cl− = Chloride.
Write the cation name first, then the anion name.
Copper(I) chloride.
Practice─Name the Following Compounds. : Tro's "Introductory Chemistry", Chapter 5 55 Practice─Name the Following Compounds. TiCl4
PbBr2
Fe2S3
Practice─Name the Following Compounds, Continued. : Tro's "Introductory Chemistry", Chapter 5 56 Practice─Name the Following Compounds, Continued. TiCl4 Titanium(IV) chloride.
PbBr2 Lead(II) bromide.
Fe2S3 Iron(III) sulfide. Cl = 4(−1) = −4
Ti = +4 = 1(4+) Br = 2(−1) = −2
Pb = +2 = 1(2+) S = 3(−2) = −6
Pb = +6 = 2(3+)
Compounds Containing Polyatomic Ions : Tro's "Introductory Chemistry", Chapter 5 57 Compounds Containing Polyatomic Ions Polyatomic ions are single ions that contain more than one atom.
Name any ionic compound by naming cation first and then anion.
Non-polyatomic cations named like Type I and II.
Non-polyatomic anions named with –ide.
Some Common Polyatomic Ions : Some Common Polyatomic Ions
Example—Writing Formula for an Ionic Compound Containing Polyatomic Ion,Iron(III) phosphate : Tro's "Introductory Chemistry", Chapter 5 59 Example—Writing Formula for an Ionic Compound Containing Polyatomic Ion,Iron(III) phosphate Write the symbol for the cation and its charge.
Write the symbol for the anion and its charge.
Charge (without sign) becomes subscript for the other ion.
Reduce subscripts to smallest whole-number ratio.
Check that the total charge of the cations cancels the total charge of the anions. Fe+3 PO43- Fe+3 PO43- Fe3(PO4)3 Fe = (1)∙(+3) = +3
PO4 = (1)∙(-3) = -3 FePO4
Practice—What Are the Formulas for Compounds Made from the Following Ions? : Tro's "Introductory Chemistry", Chapter 5 60 Practice—What Are the Formulas for Compounds Made from the Following Ions? Aluminum ion with a sulfate ion.
Chromium(II) with hydrogencarbonate.
Practice—What Are the Formulas for Compounds Made from the Following Ions?, Continued : Tro's "Introductory Chemistry", Chapter 5 61 Practice—What Are the Formulas for Compounds Made from the Following Ions?, Continued Al+3 with SO42- Al2(SO4)3
Cr+2 with HCO3─ Cr(HCO3)2
Patterns for Polyatomic Ions : Tro's "Introductory Chemistry", Chapter 5 62 Patterns for Polyatomic Ions Elements in the same column form similar polyatomic ions.
Same number of Os and same charge.
ClO3- = chlorate \ BrO3- = bromate.
If the polyatomic ion starts with H, the name adds hydrogen- prefix before it and 1is added to the charge.
CO32- = carbonate \ HCO3-1 = hydrogencarbonate.
Periodic Pattern of Polyatomic Ions-ate Groups : Tro's "Introductory Chemistry", Chapter 5 63 Periodic Pattern of Polyatomic Ions-ate Groups 3A 4A 5A 6A 7A
Patterns for Polyatomic Ions : Tro's "Introductory Chemistry", Chapter 5 64 Patterns for Polyatomic Ions -ate ion.
Chlorate = ClO3-1.
-ate ion + 1 O same charge, per- prefix.
Perchlorate = ClO4-1.
-ate ion – 1 O same charge, -ite suffix.
Chlorite = ClO2-1.
-ate ion – 2 O same charge, hypo- prefix, -ite suffix.
Hypochlorite = ClO-1.
Example—Naming Ionic with Polyatomic Ion, Na2SO4 : Tro's "Introductory Chemistry", Chapter 5 65 Example—Naming Ionic with Polyatomic Ion, Na2SO4 Is it one of the common exceptions?
H2O, NH3, CH4, NaCl, C12H22O11 = No!
Identify major class.
Na is a metal because it is on the left side of the periodic table.
SO4 is a polyatomic ion.
Ionic
Identify the subclass.
Compound has 3 elements Ionic with polyatomic ion.
Is the metal Type I or Type II?
Na is in Group 1A, Type I.
Example—Naming Ionic with Polyatomic Ion, Na2SO4 , Continued : Tro's "Introductory Chemistry", Chapter 5 66 Identify the ions.
Na = Na+ because in Group 1A.
SO4 = SO42- a polyatomic ion.
Name the cation.
Na+ = sodium (Type I).
Name the anion.
SO42- = sulfate.
Write the name of the cation followed by the name of the anion.
sodium sulfate. Example—Naming Ionic with Polyatomic Ion, Na2SO4 , Continued
Example—Naming Ionic with Polyatomic Ion, Fe(NO3)3 : Tro's "Introductory Chemistry", Chapter 5 67 Example—Naming Ionic with Polyatomic Ion, Fe(NO3)3 Is it one of the common exceptions?
H2O, NH3, CH4, NaCl, C12H22O11 = No!
Identify major class.
Fe is a metal because it is on the left side of the periodic table.
NO3 is a polyatomic ion because it is in ( ).
Ionic.
Identify the subclass.
There are 3 elements Ionic with polyatomic ion.
Is the metal Type I or Type II?
Cu is not in Group 1A, 2A, or (Al, Zn, Ag) Type II.
Example—Naming Ionic with Polyatomic Ion, Fe(NO3)3 , Continued : 68 Example—Naming Ionic with Polyatomic Ion, Fe(NO3)3 , Continued Identify the ions.
NO3 = NO3− a polyatomic ion.
Fe = Fe3+ to balance the charge of the 3 NO3−.
Name the cation.
Fe3+ = iron(III) (Type II).
Name the anion.
NO3− = nitrate.
Write the name of the cation followed by the name of the anion.
iron(III) nitrate.
Practice─Name the Following : Tro's "Introductory Chemistry", Chapter 5 69 Practice─Name the Following NH4Cl
Ca(C2H3O2)2
Cu(NO3)2
Practice─Name the Following,Continued : Tro's "Introductory Chemistry", Chapter 5 70 Practice─Name the Following,Continued NH4Cl Ammonium chloride.
Ca(C2H3O2)2 Calcium acetate.
Cu(NO3)2 Copper(II) nitrate. NO3 = 2(−1) = −2
Cu = +2 = 1(2+)
Formula-to-NameRules for Molecular : Tro's "Introductory Chemistry", Chapter 5 71 Formula-to-NameRules for Molecular We will not learn the rules for molecular compounds with more than 2 elements.
For binary molecular:
Name first nonmetal.
Then name second nonmetal with -ide ending.
Then give each name a prefix to indicate its subscript in the formula.
Binary Molecular Compounds of Two Nonmetals : Binary Molecular Compounds of Two Nonmetals Name first element in formula first.
Use the full name of the element.
Name the second element in the formula with an −ide, as if it were an anion.
However, remember these compounds do not contain ions!
Use a prefix in front of each name to indicate the number of atoms.
Never use the prefix mono- on the first element.
Subscript—Prefixes : Tro's "Introductory Chemistry", Chapter 5 73 Subscript—Prefixes 1 = mono-
Not used on first nonmetal.
2 = di-
3 = tri-
4 = tetra-
5 = penta-
6 = hexa-
7 = hepta-
8 = octa-
Drop last “a” if name begins with vowel.
Example—Naming Binary Molecular,BF3 : Tro's "Introductory Chemistry", Chapter 5 74 Example—Naming Binary Molecular,BF3 Is it one of the common exceptions?
H2O, NH3, CH4, NaCl, C12H22O11 = No!
Identify major class.
B is a nonmetal because it is on the right side of the periodic table.
F is a nonmetal because it is on the right side of the periodic table.
Molecular.
Identify the subclass.
2 elements, Binary molecular.
Example—Naming Binary Molecular, BF3 , Continued : 75 Example—Naming Binary Molecular, BF3 , Continued Name the first element.
boron.
Name the second element with an –ide.
Fluorine fluoride.
Add a prefix to each name to indicate the subscript.
monoboron, trifluoride.
Write the first element with prefix, then the second element with prefix.
Drop prefix mono- from first element.
boron trifluoride.
Formula-to-NameAcids : Tro's "Introductory Chemistry", Chapter 5 76 Formula-to-NameAcids Acids are molecular compounds that often behave like they are made of ions.
All names have acid at end.
Binary Acids = Hydro- prefix + stem of the name of the nonmetal + -ic suffix.
Oxyacids:
If polyatomic ion ends in –ate = Name of polyatomic ion with –ic suffix.
If polyatomic ion ends in –ite = Name of polyatomic ion with –ous suffix.
Practice─Name the Following : Tro's "Introductory Chemistry", Chapter 5 77 Practice─Name the Following NO2
PCl5
I2F7
Practice─Name the FollowingContinued : Tro's "Introductory Chemistry", Chapter 5 78 Practice─Name the FollowingContinued NO2 Nitrogen dioxide.
PCl5 Phosphorus pentachloride.
I2F7 Diiodine heptafluoride.
Acids : Tro's "Introductory Chemistry", Chapter 5 79 Acids Acids are molecular compounds that form H+ when dissolved in water.
To indicate the compound is dissolved in water, (aq) is written after the formula.
Not named as acid if not dissolved in water.
Sour taste.
Dissolve many metals.
Like Zn, Fe, Mg, but not Au, Ag, Pt.
Formula generally starts with H.
E.g., HCl, H2SO4.
Acids, Continued : Tro's "Introductory Chemistry", Chapter 5 80 Acids, Continued Contain H+1 cation and anion.
In aqueous solution.
Binary acids have H+1 cation and nonmetal anion.
Oxyacids have H+1 cation and polyatomic anion.
Naming Binary Acids : Tro's "Introductory Chemistry", Chapter 5 81 Naming Binary Acids Write a hydro- prefix.
Follow with the nonmetal name.
Change ending on nonmetal name to –ic.
Write the word acid at the end of the name.
Example—Naming Binary Acids,HCl : Tro's "Introductory Chemistry", Chapter 5 82 Example—Naming Binary Acids,HCl Is it one of the common exceptions?
H2O, NH3, CH4, NaCl, C12H22O11 = No!
Identify major class.
First element listed is H, Acid.
Identify the subclass.
2 elements, Binary acid.
Example—Naming Binary Acids,HCl, Continued : Tro's "Introductory Chemistry", Chapter 5 83 Example—Naming Binary Acids,HCl, Continued Identify the anion.
Cl = Cl−, chloride because Group 7A.
Name the anion with an –ic suffix.
Cl− = chloride chloric
Add a hydro- prefix to the anion name.
hydrochloric
Add the word acid to the end.
hydrochloric acid
Naming Oxyacids : Tro's "Introductory Chemistry", Chapter 5 84 Naming Oxyacids If polyatomic ion name ends in –ate, then change ending to –ic suffix.
If polyatomic ion name ends in –ite, then change ending to –ous suffix.
Write word acid at end of all names.
Example—Naming Oxyacids,H2SO4 : Tro's "Introductory Chemistry", Chapter 5 85 Example—Naming Oxyacids,H2SO4 Is it one of the common exceptions?
H2O, NH3, CH4, NaCl, C12H22O11 = No!
Identify major class.
First element listed is H, Acid.
Identify the subclass.
3 elements in the formula, Oxyacid.
Example—Naming Oxyacids, H2SO4,Continued : Tro's "Introductory Chemistry", Chapter 5 86 Example—Naming Oxyacids, H2SO4,Continued Identify the anion.
SO4 = SO42- = sulfate.
If the anion has –ate suffix, change it to –ic. If the anion has –ite suffix, change it to –ous.
SO42- = sulfate sulfuric.
Write the name of the anion followed by the word acid.
sulfuric acid
(This is kind of an exception, to make it sound nicer!)
Example—Naming Oxyacids, H2SO3 : Tro's "Introductory Chemistry", Chapter 5 87 Example—Naming Oxyacids, H2SO3 Is it one of the common exceptions?
H2O, NH3, CH4, NaCl, C12H22O11 = No!
Identify major class.
First element listed is H, Acid.
Identify the subclass.
3 elements in the formula, Oxyacid.
Example—Naming Oxyacids, H2SO3, Continued : Tro's "Introductory Chemistry", Chapter 5 88 Example—Naming Oxyacids, H2SO3, Continued Identify the anion.
SO3 = SO32- = sulfite
If the anion has –ate suffix, change it to –ic. If the anion has –ite suffix, change it to –ous.
SO32- = sulfite sulfurous
Write the name of the anion followed by the word acid.
sulfurous acid
Practice─Name the Following : Tro's "Introductory Chemistry", Chapter 5 89 Practice─Name the Following H2S
HClO3
HNO2
Practice─Name the FollowingContinued : Tro's "Introductory Chemistry", Chapter 5 90 Practice─Name the FollowingContinued H2S hydrosulfuric acid.
HClO3 chloric acid.
HNO2 nitrous acid.
Writing Formulas for Acids : Tro's "Introductory Chemistry", Chapter 5 91 Writing Formulas for Acids When name ends in acid, formulas starts with H.
Write formulas as if ionic, even though it is molecular.
Hydro- prefix means it is binary acid, no prefix means it is an oxyacid.
For an oxyacid, if ending is –ic, polyatomic ion ends in –ate; if ending is –ous, polyatomic ion ends in –ous.
Example—Binary Acids,Hydrosulfuric Acid : Tro's "Introductory Chemistry", Chapter 5 92 Example—Binary Acids,Hydrosulfuric Acid Write the symbol for the cation and its charge.
Write the symbol for the anion and its charge.
Charge (without sign) becomes subscript for the other ion.
Add (aq) to indicate dissolved in water.
Check that the total charge of the cations cancels the total charge of the anions. H+ S2- H+ S2- H2S H = (2)∙(+1) = +2
S = (1)∙(-2) = -2 H2S (aq) In all acids, the
cation is H+. Hydro- means
binary.
Example—Oxyacids,Carbonic Acid : Tro's "Introductory Chemistry", Chapter 5 93 Example—Oxyacids,Carbonic Acid Write the symbol for the cation and its charge.
Write the symbol for the anion and its charge.
Charge (without sign) becomes subscript for the other ion.
Add (aq) to indicate dissolved in water.
Check that the total charge of the cations cancels the total charge of the anions. H+ CO32- H+ CO32- H2CO3 H = (2)∙(+1) = +2
CO3 = (1)∙(-2) = -2 H2CO3(aq) In all acids, the
cation is H+. No hydro- means
polyatomic ion. -ic means -ate ion.
Example—Oxyacids,Sulfurous Acid : Tro's "Introductory Chemistry", Chapter 5 94 Example—Oxyacids,Sulfurous Acid Write the symbol for the cation and its charge.
Write the symbol for the anion and its charge.
Charge (without sign) becomes subscript for the other ion.
Add (aq) to indicate dissolved in water.
Check that the total charge of the cations cancels the total charge of the anions . H+ SO32- H+ SO32- H2SO3 H = (2)∙(+1) = +2
SO3 = (1)∙(-2) = -2 H2SO3(aq) In all acids, the
cation is H+. No hydro- means
polyatomic ion. -ous means -ite ion.
Practice—What Are the Formulas for the Following Acids? : Tro's "Introductory Chemistry", Chapter 5 95 Practice—What Are the Formulas for the Following Acids? Chlorous acid
Phosphoric acid
Hydrobromic acid
Practice—What Are the Formulas for the Following Acids?, Continued : Tro's "Introductory Chemistry", Chapter 5 96 Practice—What Are the Formulas for the Following Acids?, Continued H+ with ClO2– HClO2
H+ with PO43– H3PO4
H+ with Br– HBr
Formula-to-Name Flowchart : Tro's "Introductory Chemistry", Chapter 5 97 Formula-to-Name Flowchart