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Teaching Tips for Lesson 15: Compounds with Polyatomic Ions
Game Plan:
A. Review polyatomic ions introduced in Lesson 14.
B. Introduce formation of complex compounds by reading lesson text together. Use ion flashcards to demonstrate compound formation.
C. Play Compound Football.
D. Play Teamwork—Compound Formation version.
E. Assign Practice Pages.
F. Give Lesson 15 test.
A. Review polyatomic ions introduced in Lesson 14.
Begin class today by reviewing the many polyatomic ions learned in the last lesson and how ions join to form compounds from previous lessons.
B. Introduce formation of complex compounds by reading lesson text together. Use ion flashcards to demonstrate compound formation.
Read text together emphasizing, like compounds with monoatomic ions, the
charges of each compound constituent must add to zero. Require that your students utilize parentheses to isolate the polyatomic ions within the compound.
For those students who are not familiar with the addition of positive and negative numbers, utilize the ion flashcards to show how the polyatomic ions form compounds. Instructions for this option can be found in Lesson 13. In this lesson, you will
use the entire ion flashcard set..
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Cation Playbook
Anion Playbook
Sodium ion
Fluoride
Lithium ion
Chloride
Potassium ion
Iodide
Hydrogen ion
Bromide
Magnesium ion
Oxide
Calcium ion
Sulfide
Barium ion
Examples of Anion and Cation Playbooks—note these use very simple ions.
You will add more complex ions as your students learn the game.
~ 40 feet
Scrimmage Line
Safe Zone
for
Anions
~ 20 feet
Huddle
Area for
Anions
Position yourself here
during play.
Playing area for Compound Football Game
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Huddle
Area for
Cations
Safe Zone
for
Cations
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C: Play Compound Football! (a.k.a. Rock, Paper, Compound)
This game is a very active game which can provide many, many opportunities
for your students to practice the mental formulation of compound formulas. Begin by
dividing your students into two teams. Because the membership of each team will
continually change throughout the game, it is not necessary to divide according to
ability or size. A team captain should be chosen from each team - we usually appoint
the oldest team member to be the captain. One team should be designated as the Anions
and the other the Cations.
Each team captain will be provided with a team “playbook” which lists ions that
can be used during play. The Anion team captain should receive the Anion Playbook
while the Cation team captain should receive the Cation Playbook.
Prepare these
playbooks in advance by choosing ions that you would like your students to be able to
recall from memory. Any of the monoatomic ions could be included, and as your
students become better acquainted with the polyatomic ions, consider adding those to
their playbooks as well. Samples of playbooks are on page 234.
Choose an outdoor
playing area if possible at least 20 by 40 feet. Use flags or poles to mark the boundaries
of the playing area. A scrimmage line equidistant from either end of the playing area
should also be marked (use flour to mark this line if digging a line into the turf is not
acceptable!) Refer to page 234 for details on the playing field. An indoor gym works
equally well.
Play begins by having each team captain gather his or her teammates into a
huddle near their team’s safe zone. While in the huddle, the team chooses one ion from
their playbook for the upcoming play (the term ‘play’ being used as in a ‘football play’).
Once each team chooses its ion, players line up along the scrimmage line facing each
other like lineman on a football team.
You will serve as the referee and locate yourself on one end of the scrimmage
line. To initiate the current play, give a football cadence like, “Hut, hut, go!” On the
word “go” both teams yell the name of their chosen ion (the Anions yell-out their anion
and the Cations yell-out their cation).
What happens next depends upon the ratio
required of each ion to create a stable compound. If the compound made by the two
chosen ions can be made by a 1:1 ratio (i.e. one atom of each ion), the Cations are
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in control and chase the Anions who, in turn, quickly retreat to their safe zone. If a
Cation team member tags an Anion team member, the Anion team member becomes a
Cation team member for the next play. Anion team members who reach their safe zone
untagged, remain on the Anion team for the next play.
Should the ratio of chosen ions required to make the compound NOT be a 1:1
ratio, the Anion team is in control and they chase the Cations who, in turn, retreat to
their safe zone. Tagged Cations become Anions and play continues. With each play,
team members are exchanged until one team eventually gets “wiped-out.” If a team
dwindles too early, stop play and re-align the teams so that play can continue. Below
are some possible scenarios to help you better understand how this game is played.
Suppose the Cation team chooses the sodium ion for its play while the Anion
team chooses fluoride. Both teams come to the scrimmage line and, following your
cadence, each team yells its ion and the play unfolds. Because sodium and fluoride
create a compound with a 1:1 ratio, the Cations are in control of the play and they
chase the Anions who retreat to their safe zone. Tagged Anions now become Cations
and teams huddle for the next play.
Suppose for a second play, the Cation team chooses the calcium ion while the
Anion team chooses chloride. Both teams come to the scrimmage line and, following
your cadence, each team yells its ion and the play begins. Because calcium and chloride
do not form a compound in a 1:1 ratio (calcium chloride is Ca 1Cl2 - a 1:2 ratio), the
Anion team is in control of the play and chase the Cations who in turn retreat to their
safe zone. Tagged Cations become Anions and both teams huddle for the next play.
The key is that if the ratio of ions is 1:1, the Cations are in control and do the
chasing. If the ratio is anything but 1:1, the Anions are in control and they do the
chasing. If you find your students confused and not sure when to chase or run, point in
the direction of the safe zone where team members should run. For example, if the
Cations are in control of a play, assist all involved by pointing to the safe zone of the
Anions so that the Cations will know to chase and the Anions will know to run to their
safe zone.
Eventually, your students should be able to mentally formulate the
compound formula and know when to run or chase without your assistance. As noted
earlier, add more and more ions to each team’s playbook for added practice of
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compound formulations.
We have tremendous fun playing this game.
The momentary chaos that
inevitably ensues once a play gets underway can be quite amusing. Many times a team
will retreat just because one member chooses to run only to realize a few seconds later
that they are in control of the play and should be chasing the opposing team! If you find
it difficult to hear the ions being played, you can have your team captains whisper their
team’s choice of ion to you before lining up at the scrimmage line. This will enable you
to assist your students in which direction to run.
Because a team captain is just as likely as any other player to be tagged during
play, the oldest “surviving” team member assumes the duty of team captain and play
continues. After each play, confirm with your students the correct compound formula
so that all students are correct in their mental formulations of each compound.
You may play Compound Football with younger students who may not have
memorized many of the ions by making the following game modifications. Instead of
playbooks, position a table (a card table works well) near the safe zone for each team.
Make sure these tables are not in the path where your students may be running.
Separate a set of ion flashcards into anions and cations and then take one of each
type of card to make a set of cards for each team. On the table nearest the Cation safe
zone, spread the cation cards across the table. Do likewise with the anion cards on the
Anion table. Instead of huddling on the playing field, instruct your students to huddle
around the card tables. When in the huddle, the players should choose an ion for the
next play. The captain should then take the chosen card and hiding it in his or her hands
or shirt/jacket join his or her teammates at the scrimmage line. After the cadence, each
team yells their ion and the captains reveal the chosen cards to opposing team. Play
continues the same as in the initial variation described above.
When your younger students gain confidence using the ion cards, encourage
them to leave the chosen card on the card tables before they line up on the scrimmage
line. Eventually, suggest using a playbook as described above.
A final variation which works well when students have learned several of the
ions is, instead of allowing your students to pick their plays, is to have all team members
line up across from each other on the scrimmage line and you call out a compound
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name. Depending up the ratio of cation to anion, play continues as above.
D. Play Teamwork—Compound Formation version.
The Compound Formation Version of Teamwork is a great way to give your students tons of practice at writing compound formulas using the entire set of ions. For
this version, persons at the table farthest from you are asked to write the cation symbol
and charge. They pass their paper to persons at the next table forward who, beside the
cation, write the anion. Each team then passes their paper forward to the table nearest
you where the correct subscripts are added to make the stable compound. The paper is
then passed to you for checking. Like the other Teamwork versions you have played in
past lessons, the first team to provide you with the correct compound formula for the
compound name you called, earns two points for their team. Other teams with papers
arriving correct, but later, earn one point for their team. Papers with errors get sent back
to the table where the errors were made. Teammates can identify errors from other tables, but cannot fix them. Using different colored pens or markers at each table insures
no one “helps” when not appropriate. Play 3-4 rounds and then rotate your students to
new tables. Team points may be earned as bonus points on later quizzes or tests at your
discretion.
E. Assign Practice Pages.
F. Give Lesson 15 test.
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NAME_______________________________________ DATE___________________
FRIENDLY CHEMISTRY
Lesson 15 Test
Forming Compounds from Polyatomic Ions
Write the correct compound formula for each compound name listed below.
Compound Name
Compound
Formula
Compound Name
1. barium hydroxide
11. calcium sulfite
2. calcium nitrate
12. strontium carbonate
3. ammonium sulfate
13. lead (II) hypochlorite
4. mercury (II) chlorite
14. chromium acetate
5. aluminum phosphate
15. potassium permanganate
6. silver oxide
16. magnesium chlorate
7. copper (I) cyanide
17. nickel sulfide
8. potassium sulfite
18. lithium chromate
9. hydronium nitrite
19. ammonium dichromate
10. hydrogen peroxide
20. aluminum perchlorate
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Compound
Formula
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Write the correct compound name for each formula given below.
Formula
Compound Name
Formula
21. Na(NO3)
26. Pb+2(Cl)2
22. Ba(CO3)2
25. Zn(ClO4)2
23. K(MnO4)
28. Ca(CN)2
24. Mg(SO4)
29. (NH4)2O
25. Ni(ClO3)2
30. Al(OH)3
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Compound Name
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Lesson 15:
Making Compounds with
Polyatomic Ions
Forming compounds with polyatomic ions is very similar to the way monoatomic ions form compounds. You must remember that the polyatomic ions (although made
of more than one individual element) function as one unit. The charge given to the polyatomic ion is for the whole ion and not any individual portion. Let’s look at some examples of how compounds made with polyatomic ions form.
Sodium hydroxide is a compound commonly known as lye which is used to unclog drains and to make lye soap. The ions which make sodium hydroxide are the cation sodium and the anion hydroxide.
Sodium
Na+1
Hydroxide
(OH)-1
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To make the compound sodium hydroxide, we would need to use one sodium
ion and one hydroxide ion. In doing so, the sum of the charges equals zero. Recall, also, that it is customary to write the cation first, followed by the anion.
Na+11(OH)-11
Note that one sodium ion can
bond with one hydroxide anion to
form sodium hydroxide.
Let’s look at some more examples. Calcium carbonate is the chemical which
makes up the shells of many ocean creatures. Another name for fossilized calcium carbonate is limestone. The constituents of calcium carbonate are the calcium cation and
the carbonate anion.
Calcium
Ca+2
Carbonate
(CO3)--2
In order to make the compound calcium carbonate, the charges of the ions must
add up to zero. In this case, using one atom of each ion will result in a total charge of
zero.
Ca+21(CO3)--21
Note that one calcium cation can
bond with one carbonate anion to
form calcium carbonate.
Here is another example. Hydrogen peroxide is a well-known antiseptic solution used to “bubble-out” impurities in shallow wounds. The hydrogen peroxide compound is composed of the hydrogen cation and the peroxide anion.
Hydrogen
H+1
Peroxide
(O2)-2
If we take one hydrogen cation and one peroxide ion, the sum of the charges
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does not add up to zero. We must take a multiple of one or both of the ions in order for
the sum of the charges to equal zero. In this case, taking two hydrogen cations (each
with a +1 charge) and one peroxide anion (with its -2 charge) will result in a total charge
of zero.
H+12(O2)-21
Note that it takes two hydrogen
atoms for each peroxide anion to
create the stable hydrogen peroxide
compound.
And here is a final example. The chemical formula for rust is iron (III) oxide.
The iron (III) oxide compound is composed of the iron (III) cation and the oxide anion.
Recall that ions with a Roman Numeral as part of their name, tell you the charge of the
cation. In this case iron (III) is Fe+3.
Iron (III)
+3
Oxide
O-2
Fe
Forming this compound is a little more challenging. In order to get our charges
to add to zero, we must take two iron (III) cations and three oxide cations.
Fe+32 O-23
Note that it takes two iron (III) cations
along with three oxide anions to form
rust!
Practice making compounds by completing the practice pages which follow.
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Name_________________________________
Date___________________
Friendly Chemistry
Lesson 15: Compound Writing Practice
Below you will see a list of compounds. Write the chemical formula for each compound. Refer to your Master Ion List or flashcards if necessary.
Compound Name
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Chemical Formula
Compound Name
1. Sodium chloride
21. Barium hydroxide
2. Potassium nitrate
22. Calcium nitrite
3. Lithium chloride
23. Cesium sulfate
4. Barium sulfite
24. Nickel nitrate
5. Calcium carbonate
25. Calcium oxide
6. Strontium oxide
26. Sodium bromide
7. Tin (IV) sulfate
27. Silver chromate
8. Hydrogen chlorate
28. Copper (II) fluoride
9. Potassium perchlorate
29. Potassium permanganate
10. Aluminum acetate
30. Lithium carbonate
11. Magnesium sulfite
31. Nickel cyanide
12. Mercury (II) bromide
32. Lead (II) hypochlorite
13. Sodium dichromate
33. Zinc chlorite
14. Strontium iodide
34. Hydrogen peroxide
15. Ammonium dichromate
35. Copper (I) sulfite
16. Potassium chloride
36. Hydronium sulfide
17. Chromium perchlorate
37. Nickel phosphate
18. Calcium cyanide
38. Mercury (II) carbonate
19. Barium chlorite
39. Tin (IV) sulfate
20. Ammonium chloride
40. Potassium hydroxide
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Chemical Formula