CHM 2045C Module Four Assignment Outline-KOTZ
Module Four covers four parts of Chapter 9 and most of Chapter 3. If you use the grading outline, the key reference sections are listed under each part:
McMurray Cross Reference Stops Here 6/3/09 Kotz follows:
A. _____(05) Bond Recognition/Compound Classification-Sections ††††
C. _____(05) Binary Molecular(Covalent) Compounds-Section 3.4†
M. _____(25) Multiple Choice† Kotz Online††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††††† †††
_______(100) Total = ______%
Now that you have completed section 9.1 in Module Three and can draw the Dot Structure of Any Representative Element on the Periodic Chart, it is time to make Ionic or Covalent Compounds.
Part A: Bond Recognition
Read the short discussion in section 9.2 on pages 176-77 on the difference between Ionic and covalent bonding. However, section 9.3 is a little complicated with a discussion of the thermodynamic reason ionic compounds exist. You will not be tested on this discussion on Exam#2, especially the Multiple choice.
There are three types of chemical bonds, Ionic, Covalent, and Metallic.
There is a simpler way to predict if two atoms will transfer their electrons or share their electron in pairs making a compound. Skip back to page 409. Read about the Paulingís Scale of Electronegativities. Figure 9.14 shows the electronnegativity of each element on the periodic chart. This table will be needed in Module Four Part II Bond Polarity.
If the difference in electronegativity between two atoms is greater than 1.7, the electrons will transfer from one atom to the other to make ions and Ionic Compounds. Ionic (sometimes called Electrovalent) Compounds are also called salts and in nature they are called minerals. We will over simplify this concept to say if a metal meets a nonmetal ionic bonds are formed (if a table of electronegativity is not included).
If the difference between the electronegativites of two atoms is less than 1.7 then the two atoms will share electrons in pairs. Two types of sharing bonds are formed. Metallic and Covalent.
Metallic Bonds are formed when two metals share electrons such as alloys of metals. 24 karat gold is pure gold and is very soft. But Jewelry is usually 10-18 Karat Gold, meaning that another metal is mixed with gold to make the solid harder. We will not study Metallic Bonds in this course, but you should know that two metals share electrons in pairs to make Metallic Bonds.
Covalent Bonds are formed when two nonmetals bond together. The elements carbon, oxygen, hydrogen, sulfur, nitrogen, phosphorus, chlorine, and bromine will be the main nonmetals studied in drawing dot structures of molecules. Bonds between these nonmetals are always Covalent.
Part A of Module Four should now be easy. Predict what type of bond will be made if two atoms combine:
Metal-Metal = Metallic Bond
Metal-Nonmetal = Ionic Bond
Nonmetal-nonmetal = Covalent Bond
Part B: Dot Structures of covalent Compounds
Section 9.4, pages 382-390, is critical for you to be able to do Part B: Dot Structures of Covalent Compounds. For a take home Laboratory Assignment, you are to draw the dot structures for all the Compounds listed on Module Four Part B. You should alternate using colored pencils (pens) when showing the bonding between the two atoms. Each atom should be a different color. We will only draw the dot structures of covalent compounds which follow the octet rule (duet rule for hydrogen) for this section. There is a good tutorial Screen 9.8 in the ChemistryNOW web site or CD-ROM. Pages 383 and 384 give a set of rules for drawing the dot structures of Covalent Molecules. There is an interactive drag and drop web site for these molecules. Draw the following dot structures of the 30 molecules below:
1. NH3 CH4
H2O (all single
2. H2SO4 H3PO4 HClO4 HClO3 (all single bonds)
3. HNO3 H2CO3 HNO2 (contains one
4. CO2 HCN CO SO3 (contains at least one multiple bond)
5. HC2H3O2 H2C2O4 HCHO2 CH2O (carbon to carbon by single covalent bond in first two)
6. C2H4 C2H2 C3H8 C4H10 C2H6 (bond carbons to carbon BUT MAY HAVE A MULTIPLE BOND)
7. CH3CH2OH CH3COCH3 (carbon to carbons by single covalent bonds )
8. CH3OCH3 (Oxygen separates the carbons) CHONH2 (O & N both bond to C)
9. CH2NH2COOH (carbon to carbons by single covalent bonds (-NH2 hooks to 1st carbon in#1)
10. CH3COOCH2CH3 (-CH2CH3 also hooks to oxygen in#2)
The dot structure of
molecules interactive drag and drop web site menu page is:
Part E: Polyatomic Ions
The discussion on page 388 on Oxyacids (listed above) and their anions should be carefully read.
The web sites for Polyatomic
Ions are on your home page. Go to Polyatomic ion study guide:
It goes through my rules for polyatomic ions and has links to the other pages. However, if you chose to memorize the polyatomic ions, then you are responsible for all the polyatomic ions on page 107 Table 3.1. Module 4 Parts E, F,G,H will use these polyatomic ions. The interactive practice web sites may contain more, but your M-4 exam will only use the ions in Table 3.1
Parts D & F: Binary/Ternary Ionic Compounds
For M-4 D&F there are two interactive homework web sites and is covered in section 3.3 of the text:
Binary Ionic: http://www.lsua.us/chem1001/dragdrop/menu.html
A brief tutorial for Part D:
PART D: BINARY (IONIC) COMPOUNDS
The element written first in either the name or the formula is a metal. The element written second is a nonmetal. Salts are metallic and nonmetallic ionic compounds. There are no molecules of salts-just macro ionic lattices. Name the metallic element. If the metallic element has more than one ionic state, write a ROMAN NUMERAL after the elementís mane to indicate which charge state the metallic element is using to form the compound.
Drop the suffix off the nonmetalís name and add -ide which indicates the salt is binary
(exceptions: cyanide & hydroxide which are polyatomic ions).
No prefixes are used to indicate how many atoms are present in the formula.
NaCl Sodium Chloride (table salt)
Al2O3 Aluminum oxide
Fe2O3 Iron III oxide (rust)
To write the formula from the name of the salt use the following procedure:
(a) Write the symbols (or formulas for radicals) of the ions represented
(a) Ca P
(b) Use the periodic chart to write the ion charge of each element (or polyatomic ion) as superscripts:
†††††††††††††††††††††††††††††††††††††††††††††††††††† Ca+2 P-3
(c ) Find the L.C.M. (Least common multiple) of the positive and negative charge.
The LCM is the smallest number that both charges will dicide into evenly. The LCM is the total electrons transferred. Therefore, it represents the total positive charge created by the metallic ions and the total negative charge created by the nonmetallic ions. This may be proved by drawing the dot structure of the compound showing all electrons transferred.
The LCM of +2 and -3 is 6, therefore 6 e-1 are transferred creating a total positive charge of +6, and the total negative charge of -6
(d (d) Divide the LCM by the positive charge, this dividend will represent the subscript behind the metallic ion in the formula.
+6 divided by +2 = 3; therefore half of the formula is: Ca3Px
(e) Divide the LCM by the negative charge, this dividend will represent the number of nonmetallic ions in the formula.
-6 divided by -3 = 2; therefore the other half of the formula is: Ca3P2
Example: Potassium nitride
Ba+2 O -2 Cu +††††††††††††††††††††††††††††††††††††††† K+1 N -3
† LCM: 3
Ba+2 O -2
Cu +1 S
††††††††††††† Balance the chemical formula:
In addition to working the sample tests, you may want to practice on writing the names and formulas for Ionic Compounds.
On page 133, questions 19 thru 24 are good practice. To see if you understand the ionic charge concept try problems 11 thru 18 on page 133
Part C Binary Molecular Compounds
Binary Molecular compounds are explained after the ionic compounds in Chapter 3 section 3.4, and inorganic acids are not really covered in Chapter 3, nor in chapter 5.
The Online Binary covalent Molecules Homework has a glitch. It freezes after working through several samples. There are 31 total items. Just restart if it freezes.
The web site
Here is a brief tutorial for Part C:
PART C: BINARY COVALENT COMPOUNDS
Both elements are nonmetals attached by covalent bonds. These bonds may be single, double, or triple covalent. Due to the covalent bonding there are many ratios of the same two elements making many different compounds. For this reason, the chemist states how many atoms of each element is present in the chemical formula in the formal name of the compound.
Prefixes are attached to each element to indicate how many. Each student should learn the following prefixes:
MONO = ONE HEXA = SIX
DI = TWO HEPTA = SEVEN
TRI = THREE OCTA = EIGHT
TETRA = FOUR NONA = NINE
PENTA = FIVE DECA = TEN
The element that is shown first in the chemical formula is written first using the proper prefix to indicate how may atoms of that element is contained in the compound. If there is only one atom of that element it is often found without the prefix mono. If you leave the prefix off then it is understood that you mean mono.
The element which is written second in the chemical formula is written second in the chemical name, but in addition to the prefix indicating how many, the suffix of the elementís name is changed to -ide.
carbon becomes carbide chlorine becomes chloride
sulfur becomes sulfide oxygen becomes oxide
hydrogen becomes hydride nitrogen becomes nitride
Therefore, the following formulas of binary compounds would be spoken:
CCl4 carbon tetrachloride
SO2 sulfur dioxide
CO2 carbon dioxide
N2O3 dinitrogen trioxide
BH3 boron trihydride
For more practice on page 133-4 try problems 27 thru 30 for binary nonmetal compounds.
Part G: Binary Ternary Acids
There is a Binary/Ternary Acid online homework for your practice for M-4 Part G:
Your text does not have a section on how to name acids. The author waits till section 5.3 to introduce an acid. Table 5.2 on page 187 lists some common acids and bases. I assume that the author expects you to know the process from a prerequisite chemistry, especially CHM 1025C.
tutorial for names and formulas of acids follows:
If hydrogen is written first in a chemical formula, there is two ways to name the compound. As a pure molecular compound or as an aqueous acid:
If the compound is a pure molecular compound then you name it just as if it were an ionic compound:
HCl hydrogen chloride
HClO hydrogen hypochlorite
HClO2 hydrogen chlorite
HClO3 hydrogen chlorate
HClO4 hydrogen perchlorate
H3PO4 hydrogen phosphate
H2CO3 hydrogen carbonate
H2SO4 hydrogen sulfate
H2SO3 hydrogen sulfite
HC2H3O2 hydrogen acetate
Writing hydrogen first in a chemical formula indicates that when you dissolve the compound in water, a water molecule has the ability to pull the hydrogen (from strong electronegative elements like oxygen) off the molecule HXO3 and creating hydronium ions, H3O1+ and a negaive ion XO31- (cation). The way you indicate this ionic solution is to write the formula followed by (aq) meaning a water solution: HXO3 (aq) .
The first step is to drop the first word hydrogen and add a second word acid:
hydrogen chloride acid (aq)
hydrogen hypochlorite acid (aq)
hydrogen chlorite acid (aq)
hydrogen chlorate acid (aq)
hydrogen perchlorate acid (aq)
hydrogen phosphate acid (aq)
hydrogen carbonate acid (aq)
hydrogen sulfate acid (aq)
hydrogen sulfite acid (aq)
hydrogen acetate acid (aq)
The next step is is to drop the suffix from the cation and make the following substitution with another suffix:
Change the -ate to -ic
Change the -ite to -ous
but the instead of coming up with a third suffix for -ide , they reused the -ic for -ide and added a prefix hydro- (Do not get this confused with the prefix hypo- which means 'under'.)
HCl chloric acid (aq)
HClO hypochlorous acid (aq)
HClO2 chlorous acid (aq)
HClO3 chloric acid (aq)
HClO4 perchloric acid (aq)
H3PO4 phosphoric acid (aq) (Put the -or- syllable back in the name)
H2CO3 carbonic acid (aq)
sulfuric acid (aq) (Put the -
H2SO3 sulfurous acid (aq) (Put the -
HC2H3O2 acetic acid (aq) (Notice the three hydrogens written after carbon are NOT ionizable and not written first in the formula)
Part H: Inorganic Compounds
For Part H, we mix the compounds from Parts C, D, F, and G. There is a long interactive homework for Part H at:
The key to deciding which system to use in Part H is to look at the element written first.
1. If a Metal is written first (or a polyatomic ion), then use the rules for ionic compounds (salts).
2. If a nonmetal is written first, then use the Covalent/Molecule System with prefixes. (If the compound is Organic Nomenclature of Organics is covered in Chapter 11, but for now use the prefix system of binary molecular nomenclature.
3. If hydrogen is written first (and it is in aquous solution) then name it as an Acid
Sections 3.5, 3.6, and 3.7 will be covered in Module 5. So for now skip these sections of Chapter 3 until next Module.
Now there is a second sample Module 4 exam posted for you to practice you names and formulas: