Teacher
Naming Ionic Compounds
NGSSS:
SC.912.P.8.7: Interpret formula representations of molecules and compounds in terms of
composition and structure. Write chemical formulas for simple covalent (HCl, SO2, CO2, and
CH4), ionic (Na+ + Cl− → NaCl) and molecular (O2, H2O) compounds. Predict the formulas of
ionic compounds based on the number of valence electrons and the charges on the ions.
Purpose of Lab/Activity:
 To assemble and create as many different and non-repeating compounds as possible
using the ion/polyatomic ion template
 Based on the charges of the ions, apply the concept that a compound must have a net
charge of zero
 To be able to write the names of simple ionic formulas that use ions and polyatomic ions
Prerequisite: Prior to this activity, the student should be able to:
 Interpret formula representations of molecules and compounds in terms of composition
and structure.
 Write chemical formulas for simple covalent (HCl, SO2, CO2, and CH4), ionic (Na+, Cl−
→ NaCl) and molecular (O2, H2O) compounds.
 Predict the formulas of ionic compounds based on the number of valence electrons and
the charges on the ions so that the net charge of the compound is zero.
Materials (individual or per group):
 Ion/polyatomic ion template paper
 1 or more color pencils
 scissors
 glue stick
 copy paper
*This activity is preferably performed by 1 individual student although the activity can be
performed with a group consisting of 2 students.
Procedures: Day of Activity:
What the teacher will do:
a. Review the concept that ions and polyatomic ions can gain or lose
electrons to take a certain charge.
b. Review the concept that compounds must have a net charge of zero.
c. Show students how to construct several compounds using the ions in the
template. Demonstrate that you cannot mix different types of positive ions
Before
or different types of negative ions when making a simple compound.
activity:
d. Review the rules for naming ionic compound and review the rules for
naming compounds with polyatomic ions.
e. Question the class using several examples of different ions with different
charges and have the students create new compounds while incorporating
the previous rules discussed.
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Teacher
During
activity:
After
activity:
f. Write on the board the following procedures for the lab:
1. Positive ions are colored completely
2. Negative ions are half-colored. (Draw a diagonal line in each
negative ion box, and shade in the bottom half using a color-pencil.)
3. Cut out all of the boxes from the ion/polyatomic ion template.
4. Preassemble compounds on the students’ desks following the rules
that no two compounds can be repeated and that the net charges of
each compound must equal to zero, and that the positive portion of
the compound precedes the negative portion.
5. Glue the compounds to a sheet of paper allowing for space to write
the name of each compound.
6. Name all compounds using the nomenclature for ionic compounds
and polyatomic
g. Write on the board the (suggested) grading rubric: A = 33 or more unique
and correct compounds, B = 32 or 31 unique and correct compounds, C =
30 or 29 unique and correct compounds.
What the teacher will do:
a. Ensure that students are following the procedures and are progressing with
each of the steps of the lab in a timely manner.
b. Probe the thinking behind the creation of the compounds: “Are the students
assembling the compounds with the positive ion first and the negative ion
second?” Are students mixing different polyatomic ions in the positive side
and in the negative side, or are instead using just one type of polyatomic
ion in each side?
c. Are compounds created so that each one has the least amount of ions
(reduced) and not a multiple of the same ion?
d. Ask the students if they have used the maximum amount of ion blocks so
that no further combinations are possible.
e. Ask the students to name each compound once they have glued the
assembled compounds on their paper.
What the teacher will do:
a. Ask the students how could the design of this experiment be improved?
b. What way(s) could students make their search for new compounds more
efficient?
c. Can students create a similar exercise for other students using different
ions and a similar grading rubric?
Extension: Ask students to make various (5 positive and 5 negative) ions and polyatomic ions
using index cards, and while working with a partner, make new correct compounds which could
then be named.
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Student
Naming Ionic Compounds
NGSSS: SC.912.P.8.7: Interpret formula representations of molecules and compounds in terms
of composition and structure. Write chemical formulas for simple covalent (HCl, SO2, CO2, and
CH4), ionic (Na+ + Cl− → NaCl) and molecular (O2, H2O) compounds. Predict the formulas of
ionic compounds based on the number of valence electrons and the charges on the ions.
Background:
Once an atom "ionizes" (gives up or captures valence electrons) the ion has a (+) or (-) charge.
When two oppositely charged ions come together they bond chemically, meaning they are
electrostatically attracted to each other. In order to write the correct chemical formula we need
to make sure all the (+) and (-) charges cancel each other out so that the net charge of the
compound is zero.
The math here is very straightforward - every negative charge has to be balanced out by a
positive charge. This is what makes compounds charge neutral.
The easiest compounds to balance the charges are the ones with a 1:1 charge ratio.
 Lithium's ion Li1+ bonds with chlorine's ion Cl1- to form Lithium Chloride, LiCl.
 Magnesium's ion Mg2+ bonds with oxygen's ion O2- to form Magnesium oxide, MgO.
 Aluminum's ion Al3+ bonds with nitrogen's ion N3- to form Aluminum nitride, AlN
Notice that you don't see any subscripts in the chemical formulas above because we don't write
subscripts for compounds whose charges already equal to zero.
When you don't have a 1:1 ratio you have to find the combination that balances all of the
charges
 Lithium's ion Li1+bonds with oxygen's ion O2- to form Lithium oxide, Li2O
 Magnesium's ion Mg2+ bonds with nitrogen's ion N 3- to form Magnesium nitride, Mg3N2.
 Aluminum's ion Al3+ bonds with chlorine's ion Cl1-to form Aluminum chloride, AlCl3
Let's walk through one visually
Here 2+ and 3- will both
Ask yourself (self?) what
divide evenly into 6 so
number will both charges
your target numbers are
divide evenly into?
6 and -6.
Since 6 and -6 will
cancel to 0 divide each
target by the charge to
get each subscript.
The final formula. Wasn't
that easy?
Monoatomic vs. polyatomic ions and the compounds they form
All of the examples above contained monoatomic ions (ions with ONE element). But nature is
full of polyatomic ions, too. Polyatomic ions are made up of more than one element. Polyatomic
ions include ions like NO31- (the nitrate ion) and CO32- (the carbonate ion).
The idea of charge balancing compounds with polyatomic ions is the same. You just need to be
careful about using parentheses as needed. The general rule is: If you only need 1 of the
polyatomic ions then you don't need to surround them with a parentheses. If you need 2 or more
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Student
of a polyatomic ion then you do need to put them in parentheses so it's clear which subscript
belongs to the polyatomic ion and which subscript is there as the charge balancing "inventory"
number. Here are some example:
 Lithium's ion Li1+bonds with the nitrate ion NO31- to form Lithium nitrate LiNO3
 Magnesium's ion Mg2+ bonds with the nitrate ion NO31- to form Magnesium nitrate
Mg(NO3)2
 Aluminum's ion Al3+ bonds with the carbonate ion CO32- to form Aluminum carbonate
Al2(CO3)3
Notice you still start by looking for that lowest common multiple to find your target number. Once
you have your targets, divide each target by the charge on the associated ion to find the
subscript.
Purpose of Lab/Activity:
 To assemble and create as many different and non-repeating compounds as possible
using the ion/polyatomic ion template
 Based on the charges of the ions, apply the concept that a compound must have a net
charge of zero
 To be able to write the names of simple ionic formulas that use ions and polyatomic ions
Safety: Always wear safety goggles in the lab.
Vocabulary: Formula, ionic compounds, net charge, ion, polyatomic ion, valance electrons,
charge
Materials (individual or per group):
 Ion/polyatomic ion template paper
 1 or more color pencils
 scissors
 glue stick
 copy paper
Procedures:
1. Using the ion/polyatomic ion template, color the positive ions completely
2. Negative ions are half-colored. Draw a diagonal line in each negative ion box, and
shade in the bottom half for each negative ion.
3. Cut out all of the boxes from the ion/polyatomic ion template.
4. Preassemble compounds on your desk following the rules that no two compounds can
be repeated, and that the net charges of each compound must equal to zero.
5. Glue the compounds to a sheet of paper.
6. Name all compounds using the rules for nomenclature of ionic compounds and
polyatomic ions
7. Cleanup and Disposal- Follow your teacher's instructions for returning the coins.
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Student
Observations/Data: Use the following Ion/Polyatomic Ion Template for the lab
Ion/Polyatomic Ion Template
SO32SO32SO32SO32SO32SO32NO2NO2NO2NO2NO2NO2K+
K+
SO42-
PO43-
PO33-
OH-
PO43-
PO33-
OH-
PO43-
PO33-
OH-
PO43-
PO33-
OH-
PO43-
PO33-
OH-
PO43-
PO33-
OH-
CO32-
NH4+
Ca2+
NO3-
CO32-
NH4+
Ca2+
NO3-
CO32-
NH4+
Ca2+
NO3-
CO32-
NH4+
Ca2+
NO3-
CO32-
NH4+
Ca2+
NO3-
CO32-
NH4+
Ca2+
Be2+
B3+
P5+
Mg2+
Be 2+
B3+
P5+
Mg2+
SO42SO42SO42SO4
2-
SO42NO3-
Na+
Ba+2
Na+
Ba+2
Na+
Ba+2
Na+
Ba+2
Na+
Ba+2
Na+
Ba+2
Al3+
Pb4+
Al3+
Pb4+
Al3+
Pb4+
Al3+
Pb4+
Al3+
Pb4+
Al3+
Pb4+
Mg2+
Mg2+
Data Analysis/Results:
1. Use your own words to describe how you organized your thoughts when you carried out
this experiment?
2. How could you make the lab more efficient?
3. Predict what would happen if you used large ion combinations instead of smaller ion
combinations in making compounds.
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Student
Conclusions:
1. List and describe at least 3 sources of error observed during this activity that could have
led to poor results.
2. Use your knowledge for ionic nomenclature to name each compound listed.
a. Na3N ______________________
b. CaF2 ______________________
c. FeO ______________________
d. Al2S3 ______________________
e. MgSe ______________________
f. CoBr2 ______________________
g. CuCl2 ______________________
h. LiBr ______________________
i. SnS2 _______________________
j. Sr3P2 ________________________
3. Write the names for each of the following compounds that use polyatomic ions.
a.
b.
c.
d.
e.
f.
NaNO3 ______________________
BaSO4 ______________________
Fe2O3 ______________________
CrPO3 ______________________
(NH4)2O_____________________
RbNO2 ______________________
4. Write the correct symbols with the correct subscripts for each of the following
compounds.
a.
b.
c.
d.
e.
f.
g.
h.
i.
Aluminum phosphate ______________________
Potassium nitrate ______________________
Sodium hydrogen carbonate ______________________
Calcium carbonate ______________________
Magnesium hydroxide ______________________
Ammonium nitrate ______________________
Tin(II) nitrate ______________________
Iron(III) phosphate ______________________
Copper(I) sulfate ______________________
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