Chemical Nomenclature Part 11
Binary Compound (Metal/Nonmetal) with
Variable Charge Cation: Common Name
System
Given Formula, Write the Name
Common Name System
A binary compound is one made of two different elements. There can be one of each
element such as in CuCl or FeO. There can also be several of each element such as Fe2O3
or CuBr2.
This lesson shows you how to name binary compounds (using the common naming
system) from the formula when a cation of variable charge is involved. The four formulas
above are all examples of this type. Important point to remember: the cations involved in
this lesson have variable charges. The anions involved have only one charge.
Antoine Laurent Lavoisier (1743-94) reformed chemistry in the late 1700's with his
publication of Méthode de nomenclature chimique in 1787 (along with three co-authors)
and Traité élémentaire de Chimie in 1789. He is known as the "Father of Modern
Chemistry."
Two typical names of chemicals up to this point in history are "foliated earth of tartar"
and "phlogisticated vitriolic acid." There were hundreds of such names. One goal of the
Méthode was to create chemical names based on the chemical composition.
Lavoisier's solution, which will be studied in this lesson, was to use different suffixes to
indicate differences in composition. Specifically, the use of "-ous" and "-ic" will be
studied.
Here is what the IUPAC currently says about this naming system: "The following
systems are in use but not recommended: The system of indicating valence by means of
the suffixes -ous and -ic added to the root of the name of the cation may be retained for
elements exhibiting not more than two valences."
By the way, this picture of Lavoisier is a detail from a larger painting. In it, he is looking
up toward his wife.
1
In everything that follows, remember this overall guiding principle: the total positive
charge MUST equal the total negative charge.
All names such as "ferrous" or "plumbic" are given in the Nomenclature Data Sheet. This
is what is handed out in the Chemists's classroom. Feel free to download it, clean it up in
your word processor and use it. Print off a few extra to share with others. The Chemists
thanks you.
In the past, some students have asked for a list of roots. Here is a small list.
Element root
Element
iron
"ferr-"
chromium "chrom-"
lead
"plumb-"
tin
"stann-"
copper "cupr-"
cobalt
"cobalt-"
gold
manganese "mangan-"
"aur-"
root
mercury "mercur-"
Example #1: FeO
Step #1 - the first part of the name is the root of the first element in the formula plus a
suffix. For iron the root to use is "ferr-". The suffix will be either "-ous" or "-ic."
Here is how to determine the suffix.
1. multiply the charge of the anion (the O) by its subscript. Ignore the fact that it is
negative.
2. divide the result by the subscript of the cation (the Fe). This gives the positive
charge on the cation.
3. the lower of the two values for a given cation is assigned the ending "-ous" and
the higher uses the ending "-ic."
The result from (1) and (2) just above is two. (As you memorize the various charges, you
will also internalize the above three steps.)
That last part merits a repeat: the lower of the two values will use the "-ous" ending and
the higher will use "-ic." I can see you saying to yourself "How in the world do I know
which one is the lower and which one is the higher?" Answer - you will know from your
studies which one is lower and which is higher.
For example, iron takes on a +2 value and a +3 value. As you begin to learn these values,
the question of lower and higher becomes much easier. Trust me!
2
Step #2 - the anion is named in the usual manner of stem plus "ide."
The answer to this example is ferrous oxide.
Example #2: Fe2O3
When you multiply the anion's charge (negative two) by its subscript (three) and drop the
sign, you get six for an answer.
Then you divide the six by two (the iron's subscript) and you get three. This means the
charge on each iron is positive three.
Since this is the higher of the two charges, the term "ferric" is used.
The answer to this example is ferric oxide.
Example #3: CuCl2
The first part of the name comes from the first element's root: cupr-.
Two chlorides equal -2, so the Cu must be +2. "-ic" is used because +2 is the HIGHER of
the two charges copper is known to have.
The second part of the name comes from the root of the second symbol plus 'ide,'
therefore chlor + ide = chloride.
This compound is named cupric chloride.
Example #4: SnO
The first part of the name comes from the first element's root: stann-.
One oxygen = negative 2, so the one tin equals +2. The tin must equal +2 because you
must create a formula with zero total charges. "-ous" is used because +2 is the LOWER
of the two charges tin is known to have.
Second element is oxygen (from the symbol O), so the name is ox + ide = oxide.
This compound is named stannous oxide.
3
Practice Problems
Decide on a common name and then click the answer links to check your work.
Write the correct name for:
1) CrS
2) PbBr4
3) Pb3N2
4) Fe2S3
5) FeI2
6) Hg2F2
7) Cu2S
8) SnCl2
9) HgO
10) Sn3P4
Answers to Set One
1) chromous sulfide
2) plumbic bromide
3) plumbous nitride
4) ferric sulfide
5) ferrous iodide
6) mercurous fluoride [mercuric fluoride is #16 in set two]
7) cuprous sulfide
8) stannous chloride
9) mercuric oxide
4
10) stannic phosphide
Write the correct name for:
11) Cr2S3
12) PbCl2
13) Sn3N4
14) FeS
15) FeBr3
16) HgF2
17) CuS
18) SnI4
19) Hg2O
20) Pb3P4
Answers
11) chromic sulfide
12) plumbous chloride
13) stannic nitride
14) ferrous sulfide
15) ferric bromide
16) mercuric fluoride [mercurous fluoride is #6 in set one]
17) cupric sulfide
18) stannic iodide
19) mercurous oxide [mercurous peroxide is #29 in set three]
20) plumbic phosphide
5
Write the correct name for:
21) MnO
22) SnO2
23) PbO2
24) Fe2O3
25) CuI
26) Hg2Cl2
27) CuO
28) Sn3N2
29) Hg2O2 [Hint: the answer to this is different from #9 and #19. Hint: look up peroxide]
30) CuCl2
Answers
21) manganous oxide
22) stannic oxide [alternate answer = stannous peroxide]
23) plumbic oxide [alternate answer = plumbous peroxide]
24) ferric oxide
25) cuprous iodide
26) mercurous chloride
27) cupric oxide
28) stannous nitride
29) mercurous peroxide [mercurous oxide is #19 in set two]
30) cupric chloride
Given Name, Write the Formula
6
Common Name System
A binary compound is one made of two different elements. There can be one of each
element such as in CuCl or FeO. There can also be several of each element such as Fe2O3
or CuBr2.
This lesson shows you how to write the formula of a binary compound when given the
name using the common naming system. This means a cation of variable charge is
involved. The four formulas above are all examples of this type. Important point to
remember: the cations involved in this lesson have variable charges. The anions involved
have only one charge.
Antoine Laurent Lavoisier (1743-94) reformed chemistry in the late 1700's with his
publication of Méthode de nomenclature chimique in 1787 (along with three co-authors)
and Traité élémentaire de Chimie in 1789. He is known as the "Father of Modern
Chemistry."
Two typical names of chemicals up to this point in history are "foliated earth of tartar"
and "phlogisticated vitriolic acid." There were hundreds of such names. One goal of the
Méthode was to create chemical names based on the chemical composition.
Lavoisier's solution, which will be studied in this lesson, was to use different suffixes to
indicate differences in composition. Specifically, the use of "-ous" and "-ic" will be
studied.
Here is what the IUPAC currently says about this naming system: "The following
systems are in use but not recommended: The system of indicating valence by means of
the suffixes -ous and -ic added to the root of the name of the cation may be retained for
elements exhibiting not more than two valences."
By the way, this picture of Lavoisier is a detail from a larger painting. In it, he is looking
up toward his wife.
In everything that follows, remember this overall guiding principle: the total positive
charge MUST equal the total negative charge.
All names such as "ferrous" or "plumbic" are given in the Nomenclature Data Sheet. This
is what is handed out in the Chemist’s classroom. Feel free to download it, clean it up in
your word processor and use it. Print off a few extra to share with others. The Chemists
thanks you.
7
In the past, some students have asked for a list of roots. Here is a small list.
Element root
Element
iron
"ferr-"
chromium "chrom-"
lead
"plumb-"
tin
"stann-"
copper "cupr-"
cobalt
"cobalt-"
gold
manganese "mangan-"
"aur-"
root
mercury "mercur-"
Example #1: cuprous chloride
Step #1 - cuprous is the name of a very specific cation. It is Cu+ and nothing else.
I can see you saying to yourself "How in the world do I know that cuprous means Cu+?"
Answer - you know by your studies which cation goes with which name. If you give your
studies enough time, you will memorize all the names and charges, just like you have
memorized many other things in your life.
Step #2 - chloride is the name of a specific anion. It is Cl¯.
Step #3 - remembering thatthe total charge of the formula must be zero, you write the
formula CuCl.
Example #2: ferrous oxide
Ferrous means Fe2+.
Oxide means O2¯.
Following the usual rules, you write FeO for the formula.
Example #3: ferric sulfide
Ferric gives Fe3+.
Sulfide is S2¯.
The formula is Fe2S3
8
Keep the charge crossing technique in mind as you think about how this formula was
made. Specifically, examine the aluminum oxide example.
Example #4: stannic phosphide
Stannic means Sn4+. Just like "apple" or "light bulb" mean specific things
Phosphide means P3¯.
Sn3P4.
Example #5: mercurous chloride
Mercurous means Hg22+
Chloride means Cl¯.
Hg2Cl2.
This formula is not reduced.
Practice Problems
Write the correct formula for:
1) cupric phosphide
2) auric sulfide
3) manganous chloride
4) ferric bromide
5) mercurous oxide
6) aurous nitride
7) stannous fluoride
8) ferrous iodide
9
9) mercuric oxide
10) plumbous bromide
Answers to Set One
1) Cu3P2
2) Au2S3
3) MnCl2
4) FeBr3
5) Hg2O
6) Au3N
7) SnF2
8) FeI2
9) HgO
10) PbBr2
Write the correct formula for:
11) cuprous fluoride
12) stannic sulfide
13) ferric sulfide
14) plumbous oxide
15) ferric chloride
16) stannic oxide
17) cuprous sulfide
18) mercurous chloride
19) cobaltic iodide
10
20) plumbic phosphide
Answers to Set Two
11) CuF
12) SnS2
13) Fe2S3
14) PbO
15) FeCl3
16) SnO2
17) Cu2S
18) Hg2Cl2
19) CoI3
20) Pb3P4
Write the correct formula for:
21) ferrous nitride
22) stannous bromide
23) plumbous sulfide
24) cupric oxide
25) cuprous chloride
26) mercurous nitride (requires parenthesis)
27) mercuric sulfide
28) ferrous phosphide
29) plumbic nitride
30) cupric chloride
11
Answers
21) Fe3N2 0
22) SnBr2
23) PbS
24) CuO
25) CuCl
26) (Hg2)3N2
27) HgS
28) Fe3P2
29) Pb3N4
30) CuCl2
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