Spiritwood High School – Chemistry 30
0 • Review of Chemistry 20
TUTORIAL #2 –COMPOUNDS
You might have noticed that the notes booklet you were given has two parts.
• “Part 2” (starting on page 50) deals with Molecular Compounds;
• “Part 3” (starting on page 61) deals with Ionic Compounds.
In Chem 20, you learned the differences between these two types of compounds; you should
be able to:
1. Tell the difference between the two
2. Name each type
3. Write formulas for each type
Although you won’t directly be asked these types of questions on the final exam, you will need
to know how to pick the compounds out from a question, and solve questions based on that.
Make sure you have your PERIODIC TABLE and
your TABLE OF POLYATOMIC IONS.
First, a little Chemistry 20:
Remember the "staircase" which separates metals from non-metals? (good. DRAW IT on your
periodic table; it’ll be useful later)
Using Section 2.7, answer these:
1. What is the difference between an atomic number and the atomic mass of an
element? In your explanation, use “phosphorous” to show the difference between
the two terms.
2. Where are metals found on the periodic table? Using the periodic table, explain the
two ways you can distinguish elements that have “more metallic character”.
3. Using physical properties, explain the differences between metals and nonmetals.
4. What are metalloids, and where are they found on the periodic table? What are they
used for?
5. What is special about how noble gases combine (or don’t combine).
Using Section 2.8, answer these:
1. In a chemical formula, what do the subscripts mean?
2. List the 7 diatomic gases that you need to write on the back of your periodic table and
remember, remember, remember! (are they important? Uh-huh!)
Reviewing Molecular Compounds.
Using Section 2.9, answer these:
1. On the back of your “Table of Polyatomic Ions”, write the heading “Molecular
Compound Prefixes” and write the prefix/number combinations from Table 2-4.
2. Explain how to correctly name the compound: P2O5
3. What is the only time that a prefix isn’t used for naming molecular compounds?
4. Put the answers for “Part 2 Review” in the spaces below.
#13
#14
a) _______
f) _______
b) _______
g) _______
c) _______
h) _______
d) _______
i) _______
e) _______
j) _______
a) _______
f) _______
b) _______
g) _______
c) _______
h) _______
d) _______
i) _______
e) _______
j) _______
#17
a) _________________
b) _________________
c) _________________
#18
a) _________________
b) _________________
c) _________________
Reviewing Ionic Compounds.
The other type of compound that you can expect much more of is the ionic compound. Ionic
compounds form between one _______________ and one _________________. The charged metal
ion (called a cation) has a ____________ charge and the charged non-metal ion (called an anion)
has a _____________ charge.
Using Section 2.10, answer these:
1. On your periodic table, put the charges above the groups using Rules #1 to #4 to
guide you.
•
(for example, above group 1A, put a “1+”
2. Using Example 2-2, explain how to find the formula for an ionic compound. (You may
wish to explain this using the “metal / non-metal table” we used in Chem 20.
3. What does dissociate mean? What happens when CaCl2 dissociates?
Using Section 2.11, answer these:
1. What is a polyatomic ion?
2. Show how we would write a
compound that has “1 magnesium
and 2 nitrates”
3. Show how we would write a compound
that has “2 aluminums and 3 sulfates”
4. Write the formula for magnesium
cyanide.
5. Write the formula for aluminum nitrate.
Using Section 2.13, answer these:
1. Explain why there might be confusion if we try to name FeCl2 and FeCl3. (This is the
reason for the ‘stock system’ (with Roman Numerals in brackets).
2. Write the formula for iron(III) oxide.
3. Name the following: Cu2CO3
Put the answers to “Part 3 Review” here:
#38
a) _______________________________________
b) _______________________________________
c) _______________________________________
d) _______________________________________
e) _______________________________________
#39
a) _______________________________________
b) _______________________________________
c) _______________________________________
d) _______________________________________
#41
a) _______________________________________
b) _______________________________________
c) _______________________________________
d) _______________________________________
#42
a) _______________________________________
b) _______________________________________
c) _______________________________________
How can you pick out the differences between these two compounds when you are
naming them? The following rules will help you decide:
Rules for Ionic and Molecular Solutions:
1. Compounds made up of a metal and a non-metal will form ionic solutions.
2. Compounds containing polyatomic ions will form ionic solutions.
3. Compounds containing only non-metals (covalent compounds) will form
molecular solutions.
Here they are explained in a bit more detail, with examples:
1.
Compounds made up of a metal (left side of staircase) and a non-metal
(right side of staircase) form Ionic Solutions.
NaCl forms an ionic solution. We show this by writing a dissociation equation:
NaCl(s) Na
AlCl3 forms an ionic solution:
AlCl3(s) Al
1+
(aq)
3+
(aq)
+ Cl
+ 3Cl
1(aq)
1(aq)
Both of these substances are made up of a metal and a non-metal. When they are dissolved
in water, they break up into free ions.
2. Compounds containing polyatomic ions form Ionic solutions.
KMnO4 (is made up of K
follows:
1+
1-
ions and MnO4 ions). When it is added to water, it dissociates as
KMnO4(s) K
1+
(aq)
+
1(aq)
MnO4
1-
MnO4 is a polyatomic ion called "permanganate" and is found on the Polyatomic Ion
Table.
3. Covalent Compounds (made up of a non-metal and a non-metal) generally form
Molecular solutions.
These include compounds in which both elements are found on the right side of the
staircase.
An example is the element iodine (formula is I2). When iodine dissolves in water it does
NOT break up into ions. It simply stays as neutral molecules and disperses itself in the
water. The equation for it dissolving in water would be:
I2(s) I2(aq)
Notice, there are no ions in the product, just I2 molecules, which dissolve.
Self-Test on TUTORIAL #2 - COMPOUNDS
Do this self-test right on this sheet.
1.
2.
Decide whether each of the following compounds will form an Ionic (I) solution or a
Molecular (M) solution in water. Assume that all substances dissolve at least partially.
a) NiCl2 ................................................
________________________________
b) CH3OH ..............................................
________________________________
c) CH3CH2COOH .................................
________________________________
d) Fe(NO3)3 ...........................................
________________________________
e) K2Cr2O7 ............................................
________________________________
f) C6H12O6 ............................................
________________________________
g) PCl3 ....................................................
________________________________
h) CsBr ..................................................
________________________________
i) HNO3 ................................................
________________________________
j) HCOOH ............................................
________________________________
Write an equation showing what happens when each of the following are dissolved in
water: ("a" and "b" are done as an examples)
a) Na2SO4(s) ; (ionic)
Na2SO4(s) 2Na+(aq) + SO42-(aq)
b) CH3OH(l) ; (molecular) CH3OH(l)
CH3OH(aq)
c) KCl(s) ....................... _______________________________________________________
d) NH4NO3(s).............. _______________________________________________________
e) Ca3(PO4)2(s) ............_______________________________________________________
f) CH3CH2CH2OH(l) ...._______________________________________________________
g) CH3CH2CH2COOH(l) _______________________________________________________