Chemical Nomenclature Part 111
Covalent Binary Compound (Two Nonmetals): Greek
Prefix System
Given Formula, Write the Name
The Greek System
A binary compound is one made of two different elements. There can be one of each
element such as in CO or NO. There can also be several of each element such as BF3 or
OCl2.
This lesson shows you how to name binary compounds from the formula when two
nonmetals are involved. The four formulas above are all examples of this type. Important
point to remember: NO metals (which act as the cation) are involved. That means one of
the nonmetals will be acting in the positive role while the other is negative.
In fact, you do not even need to know the charges, since the formula comes right from the
element names and their prefixes. Be aware that heavy use of Greek number prefixes are
used in this lesson.Here are the first ten:
one
two
three
four
five
monoditritetrapenta-
six
seven
eight
nine
ten
hexaheptaoctanonadeca-
Example #1 - write the name for N2O.
Example #2 - write the name for NO2.
Step #1 - part of the first name is the unchanged name of the first element in the formula.
In the examples above, it would be nitrogen.
If the subscript of the first element is 2 or more, you add a prefix to the name. In the first
example above, you would write dinitrogen. If the subscript is one as in the second
example above, you DO NOT use a prefix. You simply write the name, in this example it
would be nitrogen.
1
Step #2 - the anion is named in the usual manner of stem plus "ide." In addition, a prefix
is added. In the first example, the prefix is "mono-" since there is one oxygen. In the
second example, use "di-" because of two oxygens.
The correct names of the two examples are dinitrogen monoxide and nitrogen dioxide.
Note that "monoxide" is written rather than "monooxide." It sounds better when spoken
out loud.
Example #3 - write the name for IF7.
Step #1 - the first element is iodine and there is only one. This part of the name will be
"iodine", NOT "monoiodine."
Step #2 - the second element is fluorine, so "fluoride" is used. Since there are seven, the
prefix "hepta" is used.
The name of this compound is iodine heptafluoride.
Example #4 - write the name for N2O5.
Step #1 - the first element is nitrogen and there are two. This part of the name will be
"dinitrogen."
Step #2 - the second element is oxygen, so "oxide" is used. Since there are five, the prefix
"penta" is used.
The name of this compound is "dinitrogen pentaoxide." Many write is as "dinitrogen
pentoxide." The Chemists believes that both are considered correct, but the second is to
be prefered.
Example #5 - write the name for XeF2.
The first part of the name comes from the first element's name: xenon. Since there is only
one atom present, no prefix is used.
The second part of the name comes from the root of the second symbol plus 'ide' as well
as the prefix "di-,"therefore di + fluor + ide = difluoride.
This compound is named xenon difluoride.
2
Example #6 - write the name for N2O4.
The first part of the name comes from the first element's name: nitrogen. Since there are
two atoms, the prefix "di-" is used giving dinitrogen.
The second part of the name comes from the root of the second symbol plus 'ide' as well
as the prefix "tetra-,"therefore tetr + ox + ide = tetroxide.
This compound is named dinitrogen tetroxide. Notice the dropping of the "a" in tetra.
Just a reminder: this system of naming does not really have an offically accepted name,
but is often called the Greek system (or method). It involves use of Greek prefixes when
naming binary compounds of two nonmetals.
Sometimes you will see the Stock system applied to these types of compounds. Here is
what the IUPAC currently says about that practice: "The Stock notation can be applied to
both cations and anions, but preferably should not be applied to compounds between
nonmetals."
Practice Problems
Write the correct name for:
1) As4O10
2) BrO3
3) BN
4) N2O3
5) NI3
6) SF6
7) XeF4
8) PCl3
9) CO
10) PCl5
3
Answers to Set One
1) tetrarsenic decoxide
2) bromine trioxide
3) boron nitride
4) dinitrogen trioxide
5) nitrogen triiodide
6) sulfur hexafluoride
7) xenon tetrafluoride
8) phosphorous trichloride
9) carbon monoxide
10) phosphorous pentachloride
Write the correct name for:
11) P2O5
12) S2Cl2
13) ICl2
14) SO2
15) P4O10
16) UF6
17) OF2
18) ClO2
19) SiO2
20) BF3
Answers to Set Two
4
11) diphosphorous pentoxide
12) disulfur dichloride
13) iodine dichloride
14) sulfur dioxide
15) tetraphosphorous decoxide
16) uranium hexafluoride
17) oxygen difluoride
18) chlorine dioxide
19) silicon dioxide
20) boron trifluoride
Write the correct name for:
21) N2S5
22) CO2
23) SO3
24) XeF6
25) KrF2
26) BrCl5
27) SCl4
28) PF3
29) XeO3
30) OsO4
Answers
21) dinitrogen pentasulfide
5
22) carbon dioxide
23) sulfur trioxide
24) xenon hexafluoride
25) krypton difluoride
26) bromine pentachloride
27) sulfur tetrachloride
28) phosphorous trifluoride
29) xenon trioxide
30) osmium tetroxide
Binary Compounds of Two Nonmetals
Given Name, Write the Formula
The Greek System
A binary compound is one made of two different elements. There can be one of each
element such as in CO or NO. There can also be several of each element such as
BF<SUB3< SUB> or OCl2.
This lesson shows you how to write the formula of a binary compound from its name
when two nonmetals are involved. The four formulas above are all examples of this type.
Important point to remember: NO metals (which act as the cation) are involved. That
means one of the nonmetals will be acting in the positive role while the other is negative.
In fact, you do not even need to know the charges, since the name comes right from the
amounts of the two elements involved. Be aware that heavy uses of Greek number
prefixes are used in this lesson. Here are the first ten:
one
two
three
four
five
monoditritetrapenta-
six
seven
eight
nine
ten
6
hexaheptaoctanonadeca-
Example #1 - write the formula for dinitrogen trioxide.
Example #2 - write the name for carbon monoxide.
Step #1 - the first name will tell you the first element in the formula. In the first example
above, it would be N and in the second, C.
If there is a prefix on the name, this gives the subscript on the element. In the first
example above, the "di-" tells you there are two nitrogens. Absence of a prefix, as in the
second example, says there is only one of that element involved.
Step #2 - the anion name tells you the element; oxide means oxygen. Once again, the
prefix will tell you how many of the element are involved. "Tri-" means three and "mono" means one.
The correct formulas of the two examples are N2O3 and CO.
Note that "monoxide' is written rather than "oxide" when there is one atom of the second
element involved. Note also that when one element of the first atom is involved, no
"mono-" is used. Monocarbon monoxide is just as wrong as carbon oxide.
Example #3 - write the formula for bromine pentafluoride.
Step #1 - the first symbol is Br and its subscript will be a one, which is understoo to be
present.
Step #2 - the second element is fluorine, so F is used. The prefix "penta-" indicates a
subscript of 5.
The formula of this compound is BrF5.
Example #4 - write the formula for diphosphorous pentoxide.
Step #1 - the first symbol is P and the subscript is 2.
Step #2 - pentoxide says five oxygens are involved.
The formula of this compound is P2O5.
Example #5 - write the formula for iodine heptafluoride.
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Step #1 - the first symbol is I and the subscript is 1. Again it is understood to be there.
Step #2 - heptafluoride says 7 florides are involved.
The formula of this compound is IF7.
Practice Problems
Write the correct formula for:
1) chlorine monoxide
2) oxygen difluoride
3) boron phosphide
4) dinitrogen monoxide
5) nitrogen trifluoride
6) sulfur tetrachloride
7) xenon trioxide
8) carbon dioxide
9) diphosphorous pentoxide
10) phosphorous trichloride
Answers to Set One
1) ClO
2) OF2
3) BP
4) N2O
5) NF3
6) SCl4
7) XeO3
8
8) CO2
9) P2O5
10) PCl3
Write the correct formula for:
11) sulfur dioxide
12) bromine pentafluoride
13) disulfur dichloride
14) boron trifluoride
15) tetraarsenic decoxide
16) silicon tetrachloride
17) krypton difluoride
18) chlorine monoxide
19) silicon dioxide
20) boron trichloride
Answers to Set Two
11) SO2
12) BrF5
13) S2Cl2
14) BF3
15) As4O10
16) SiCl4
17) KrF2
18) ClO
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19) SiO2
20) BCl3
Write the correct formula for:
21) dinitrogen pentasulfide
22) carbon monoxide
23) sulfur trioxide
24) dinitrogen trioxide
25) dinitrogen monoxide
26) xenon hexafluoride
27) sulfur hexafluoride
28) phosphorous pentachloride
29) nitrogen monoxide
30) bismuth trichloride
Answers
21) N2S5
22) CO
23) SO3
24) N2O3
25) N2O
26) XeF6
27) SF6
28) PCl5
29) NO
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30) BiCl3
Polyatomics (Metal with fixed or variable
charge/Polyatomic)
Compounds Involving a Polyatomic Ion
Given Formula, Write the Name
These compounds to follow ARE NOT binary compounds. They contain three or more
elements, as opposed to only two in a binary compound.
The Greek method WILL NOT be used. That naming technique is used only for binary
compounds of two nonmetals. That means, if you see a formula like BaSO4, the name is
not barium monosulfur tetraoxide. Many unaware Chemists students over the years have
made this error and suffered for it.
Consequently, a warning: it is important that you learn to recognize the presence of a
polyatomic ion in a formula. Many of Chemists’ students have made it their first priority
to make a set of flashcards with the name on one side and the ion and its charge on the
other. Then, carry them everywhere and use them.
The cations used will be a mix of fixed charges AND variable charges. You must know
which are which.
Another warning: you must also know the charges associated with each polyatomic ion.
For example, NO3¯ is called nitrate and it has a minus one charge. Once again, many
unaware Chemists students have thought this means nitrate has a minus three charge. IT
DOES NOT.
Use of Parenthesis
When more than one polyatomic ion is required, parenthesis are used to enclose the ion
with the subscript going outside the parenthesis. For example, the very first formula used
is Fe(NO3)2. This means that two NO3¯ are involved in the compound. Without the
parenthesis, the formula would be FeNO32, a far cry from the correct formula.
When you say a formula involving parenthesis out loud, you use the word "taken" as in
the formula for ammonium sulfide, which is (NH4)2S. Out loud, you say "N H four taken
twice S." OR with the formula for copper(II) chlorate, which is Cu(ClO3)2. You say " Cu
Cl O three taken twice."
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Example #1 - write the name for Fe(NO3)2 Step #1 - decide if the cation is one showing
variable charge. If so, a Roman numeral will be needed. In this case, iron does show
variable charge.
If a variable charge cation is involved, you must determine the Roman numeral involved.
You do this by computing the total charge contributed by the polyatomic ion. In this case,
NO3¯ has a minus one charge and there are two of them, making a total of minus 2.
Therefore, the iron must be a positive two, in order to keep the total charge of the formula
at zero.
Step #2 - determine the name of the polyatomic ion. Nitrate is the name of NO3¯.
The correct name is iron(II) nitrate. The common name would be ferrous nitrate.
Example #2 - write the name for NaOH
Step #1 - the cation, Na+, does not show a variable charge, so no Roman numeral is
needed. The name is sodium.
Step#2 - OH¯ is recognized as the hydroxide ion.
The name of this compound is sodium hydroxide.
Usually, at this point, a cry is heard in the Chemist’s classroom. "But how do you know
that OH¯ is hydroxide?" is the plaintive wail. The stock Chemists answer is "Well, how
do you know anything? How do you know your phone number? How do you know your
best friend's name? In fact, how do you know your name?" There are three things you
must memorize: the name (hydroxide), the symbol (OH) and the charge (minus one). You
must put in the time to learn this nomenclature stuff. It does not come easy and the
Chemists realizes you'd rather be spending the time doing more important things: going
cool places with friends, spending time with members of the opposite sex, spending your
parents' money, sleeping, etc. Maybe some other time. Right now, let's move on.
Example #3 - write the name for KMnO4
Step #1 - the cation, K+, does not show a variable charge, so no Roman numeral is
needed. The name is potassium.
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Step#2 - MnO4¯ is recognized as the permanganate ion.
The name of this compound is potassium permanganate.
Example #4 - write the name for Cu2SO4 Step #1 - decide if the cation is one showing
variable charge. If so, a Roman numeral will be needed. In this case, copper does show
variable charge.
If a variable charge cation is involved, you must determine the Roman numeral involved.
You do this by computing the total charge contributed by the polyatomic ion. In this case,
SO42¯ has a minus two charge and there is only one, making a total of minus 2.
Therefore, the copper must be a positive one. Why? Well, there must be a positive two to
go with the negative two in order to make zero. Since the formula shows two copper
atoms involved, each must be a plus one charge.
Step #2 - determine the name of the polyatomic ion. Sulfate is the name of SO42¯.
The correct name is copper(I) sulfate. The common name would be cuprous sulfate.
Example #5 - write the name for Ca(ClO3)2
The first part of the name comes from the first element's name: calcium. You also
determine that it is not a cation of variable charge.
The second part of the name comes from the name of the polyatomic ion: chlorate.
This compound is named calcium chlorate.
Example #6 - write the name for Fe(OH)3
Iron is an element with two possible oxidation states. The iron is a +3 charge because (1)
there are three hydroxides, (2) hydroxide is a minus one charge, (3) this gives a total
charge of negative three and (40 there is only one iron, so it must be a +3.
Therefore the first part of the name is iron(III).
The second part of the name is hydroxide, the name of the polyatomic ion.
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The name of this compound is iron(III) hydroxide (or ferric hydroxide when using the
common method).
Practice Problems
The cations in this first set are all of fixed oxidation state, so no Roman numerals are
needed.
Write the correct name for:
1) AlPO4
2) KNO2
3) NaHCO3
4) CaCO3
5) Mg(OH)2
6) Na2CrO4
7) Ba(CN)2
8) K2SO4
9) NaH2PO4
10) NH4NO3
Answers to Set One
1) aluminum phosphate
2) potassium nitrite
3) sodium hydrogen carbonate [sodium bicarbonate]
4) calcium carbonate
5) magnesium hydroxide
6) sodium cromate
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7) barium cyanide
8) potassium sulfate
9) sodium dihydrogen phosphate
10) ammonium nitrate
These formulas involve the use of a polyatomic ion. The cations are all of variable
oxidation state, so Roman numerals are needed.
Write the correct name for:
11) Sn(NO3)2
12) FePO4
13) Cu2SO4
14) Ni(C2H3O2)2
15) HgCO3
16) Pb(OH)4
17) Cu2Cr2O7
18) Cu(ClO3)2
19) FeSO4
20) Hg2(ClO4)2
Answers to Set Two
11) tin(II) nitrate [stannous nitrate]
12) iron(III) phosphate [ferric phosphate]
13) copper(I) sulfate [cuprous sulfate]
14) nickel(II) acetate [nickelous acetate]
15) mercury(II) carbonate [mercuric carbonate]
16) lead(IV) hydroxide [plumbic hydroxide]
15
17) copper(I) dichromate [cuprous dichromate]
18) copper(II) chlorate [cupric chlorate]
19) iron(II) sulfate [ferrous sulfate]
20) mercury(I) perchlorate [mercurous perchlorate]
These formulas mix the use of the two types of cations.
Write the correct name for:
21) KClO3
22) SnSO4
23) Al(MnO4)3
24) Pb(NO3)2
25) Mg3(PO4)2
26) CuH2PO4
27) CaHPO4
28) Fe(HCO3)3
29) Na2CO3
30) MnSO4
Answers
21) potassium chlorate
22) tin(II) sulfate [stannous sulfate]
23) aluminum permanganate
24) lead(II) nitrate [plumbous nitrate]
25) magnesium phosphate
26) copper(I) dihydrogen phosphate [cuprous dihydrogen phosphate]
16
27) calcium hydrogen phosphate
28) iron(III) hydrogen carbonate [ferric hydrogen carbonate, iron(III) bicarbonate, ferric
bicarbonate] Yep! Gotta know all four!
29) sodium carbonate
30) manganese(II) sulfate [manganous sulfate]
Compounds Involving a Polyatomic Ion
Given Name, Write the Formula
These compounds to follow ARE NOT binary compounds. They contain three or more
elements, as opposed to only two in a binary compound.
The Greek method WILL NOT be used. That naming technique is used only for binary
compounds of two nonmetals. That means, if you see a formula like BaSO4, the name is
not barium monosulfur tetraoxide. Many unaware Chemists students over the years have
made this error and suffered for it.
Consequently, a warning: it is important that you learn to recognize the presence of a
polyatomic ion in a name. Many Chemists students have made it their first priority to
make a set of flashcards with the name on one side and the ion and its charge on the
other. Then, carry them everywhere and use them.
The cations used will be a mix of fixed charges AND variable charges. You must know
which are which.
Another warning: you must also know the formula and charge associated with each
polyatomic ion' name. For example, NO3¯ is called nitrate and it has a minus one charge.
The formula and charge are not inherent in the name.
Use of Parenthesis
When more than one polyatomic ion is required, parenthesis are used to enclose the ion
with the subscript going outside the parenthesis. For example, the very first name used is
copper(II) chlorate. The correct formula will require the use of parenthesis.
When you say a formula involving parenthesis out loud, you use the word "taken" as in
the formula for ammonium sulfide, which is (NH4)2S. Out loud, you say "N H four taken
twice S." OR with the formula for copper(II) nitrate, which is Cu(NO3)2. You say " Cu N
O three taken twice."
17
On writing the formula from the ions, you may want to review Charge-Crossing. or
Least-Common-Multiple, for more information.
Example #1 - write the formula for copper(II) chlorate
Step #1 - the first word tells you the symbol of the cation. In this case it is Cu.
Step #2 - the Roman numeral WILL tell you the charge on the cation. In this case it is a
positive two.
Step #3 - the polyatomic formula and charge comes from the second name. In this case,
chlorate means ClO3¯.
Step #4 - remembering the rule that a formula must have zero total charge, you write the
formula Cu(ClO3)2.
This graphic summarizes example #1:
Example #2 - write the formula for silver cyanide
Step #1 - the first word tells you the symbol of the cation. In this case it is Ag+.
Step #2 - silver has a constant charge of +1, it is not a cation with variable charge.
Step #3 - the polyatomic formula and charge comes from the second name. In this case,
cyanide means CN¯.
Step #4 - remembering the rule that a formula must have zero total charge, you write the
formula AgCN.
This graphic summarizes example #2:
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Usually, at this point, a cry is heard in the Chemist’s classroom. "But how do you know
that cyanide is CN¯?" is the plaintive wail. The stock Chemists answer is "Well, how do
you know anything? How do you know your phone number? How do you know your best
friend's name? In fact, how do you know your name?" There are three things you must
memorize: the name (cyanide), the symbol (CN, not Cn, by the way) and the charge
(minus one). You must put in the time to learn this nomenclature stuff. It does not come
easy and the Chemists realizes you'd rather be spending the time doing more important
things: going cool places with friends, spending time with members of the opposite sex,
spending your parents' money, eating, etc. Maybe some other time. Right now, let's move
on.
Example #3 - write the formula for plumbic hydroxide
Step #1 - the cation, Pb4+, does show a variable charge. The "-ic" ending means the
higher of the two, for this cation that means +4.
Step#2 - hydroxide is recognized as OH¯.
The formula of this compound is Pb(OH)4. Notice that it is not PbOH4.
This graphic summarizes example #3:
You might want to read about a problem with hydroxide that many students suffer from.
Example #4 - write the formula for sodium phosphate
Step #1 - the cation, sodium, is Na+, and it does not show a variable charge.
Step#2 - phosphate is PO43¯.
The formula of this compound is Na3PO4. Notice that no parenthesis are required since
only one polyatomis is used.
This graphic summarizes example #4:
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Example #5 - write the formula for mercurous nitrate
Step #1 - the cation, mercurous, does show a variable charge and its formula is unusual. It
is Hg22+. The "-ous" ending indicates the lower of the two charges mercury shows and
that is the +1 charge. Remember that, in this particular case, Hg+ is wrong.
Step#2 - nitrate is NO3¯.
The formula of this compound is Hg2(NO3)2. This formula is not reduced.
This graphic summarizes example #5:
Example #6 - write the name for barium carbonate
Step #1 - the cation, barium, does not show a variable charge and its symbol is Ba2+.
Step#2 - carbonate is CO32¯.
The formula of this compound is BaCO3.
This graphic summarizes example #6:
Example #6 - write the name for mercury(I) phosphate
Step #1 - the cation, mercury(I), does show a variable charge and its symbol is
Hg<SUB.2< sub>2+. Notice that there is a subscript of two and the charge is +2.
Therefore, EACH Hg atom is +1, leading to the name mercury(I).
Step#2 - phosphate is PO43¯.
The formula of this compound is (Hg2)3(PO4)2.
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Note the use of parenthesis around both parts (positive and negative) of the formula. It
would be incorrect to write this formula: Hg6(PO4)2. We want the formula to show that
mercury(I) comes in groups of two and that there are three of them.
Practice Problems
The cations in this first set are all of fixed oxidation state, so no Roman numerals are
needed.
Write the correct formula for:
1) silver carbonate
2) potassium hydrogen phosphate
3) aluminum hydroxide
4) sodium hydrogen carbonate
5) calcium acetate
6) potassium permanaganate
7) calcium perchlorate
8) lithium carbonate
9) magnesium hydrogen sulfite
10) sodium hypochlorite
Answers to Set One
1) Ag2CO3
2) K2HPO4
3) Al(OH)3
4) NaHCO3
5) Ca(C2H3O2)2
6) KMnO4
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7) Ca(ClO4)2
8) Li2CO3
9) Mg(HSO3)2
10) NaClO
These formulas involve the use of a polyatomic ion. The cations are all of variable
oxidation state, so Roman numerals are needed.
Write the correct formula for:
11) tin(IV) chlorite
12) mercury(II) phosphate
13) tin(II) carbonate
14) mercurous acetate
15) lead(II) chromate
16) copper(I) sulfite
17) stannous dichromate
18) iron(III) nitrate
19) ferric sulfate
20) ferrous hydroxide
Answers to Set Two
11) Sn(ClO2)4
12) Hg3(PO4)2
13) SnCO3
14) Hg2(C2H3O2)2
15) PbCrO4
16) Cu2SO3
22
17) SnCr2O7
18) Fe(NO3)3
19) Fe2(SO4)3
20) Fe(OH)2
These formulas mix the use of the two types of cations.
Write the correct formula for:
21) potassium perchlorate
22) lead(IV) hydrogen phosphate
23) aluminum sulfate
24) iron(II) bicarbonate
25) barium iodate
26) tin(II) hydrogen sulfide
27) magnesium dihydrogen phosphate
28) plumbous cyanide
29) silver phosphate
30) cobalt(III) nitrite
and two special additions:
31) ammonium sulfate
32) ammonium nitrate
Answers
21) KClO4
22) Pb(HPO4)2
23) Al2(SO4)3
23
24) Fe(HCO3)2
25) Ba(IO3)2
26) Sn(HS)2
27) Mg(H2PO4)2
28) Pb(CN)2
29) Ag3PO4
30) Co(NO2)3
31) (NH4)2SO4
32) NH4NO3
Nomenclature of Inorganic Acids
Recognizing an Acid
At this very beginning level, you will recognize an acid by the fact that its formula starts
with H, as in these examples:
HCl
HNO3
H2SO4
HClO3
H3BO3
As you become more sophisticated in your chemistry, you will realize that there are many
acid formulas that do not start with H, but those will almost all be left for another time.
There is one exception to this: the formula CH3COOH should be recognized as acetic
acid. The particular way it is written is common in organic chemistry. An alternate way
to write acetic acid is HC2H3O2. This is done in the inorganic style, which you are
currently studying.
One last comment before looking at how to name acids: the formula H2O should not be
considered an acid. It is the formula for water. It is not an acid. When you study acid-base
behavior later in the school year, you will learn more about water's role in acid-base
chemistry, but not now.
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Naming Acids
In order to explain acid naming, the sequence of HCl, HClO, HClO2, HClO3, and HClO4
will be discussed in order.
HCl is a binary acid. All binary acids are named the same way:
1.
2.
3.
4.
the prefix "hydro" is used.
the root of the anion is used.
the suffix "ic" is used.
the word "acid" is used as the second word in the name.
The name for HCl is hydrochloric acid. Other binary acids you are responsible for are
HF, HBr, HI, and H2S.
1) HClO is an acid involving a polyatomic ion. You MUST recognize the polyatomic ion
in the formula. There is no other way to figure out the name. If you don't recognize the
polyatomic, then you're sunk without a trace.
The polyatomic ion is ClO¯ and its name is hypochlorite. Any time you see the "ite"
suffix, you change it to "ous" and add the word acid.
The name of HClO is hypochlorous acid.
2) HClO2 has the ClO2¯ polyatomic ion in it. The name of this ion is chlorite.
Since the "ite" suffix is used, it gets changed to "ous."
The name of HClO2 is chlorous acid.
3) HClO3 has the ClO3¯ polyatomic ion and its name is chlorate. Any time you know the
"ate" ending is used on the polyatomic, you use "ic" when you write the corresponding
acid formula.
The name of HClO3 is chloric acid.
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4) HClO4 has the ClO4¯ polyatomic ion and its name is perchlorate.
Since the "ate" suffix is used, it gets changed to "ic."
The name of HClO4 is perchloric acid.
In the Chemists's estimation there are two keys. You have to:
1. recognize when a polyatomic is present and
2. know its name.
Only then can you know to change the "ite" suffix to "ous" and the "ate" suffix to "ic"
when it is an acid.
Practice Problems
Name the following acids:
1) H3PO4
2) H2CO3
3) H2SO4
4) HIO3
5) HF
6) HNO2
Write the formula for these acids:
7) hydrobromic acid
8) hydrocyanic acid [this has a twist in it]
9) nitric acid
10) sulfurous acid
11) phosphorous acid
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12) acetic acid
1) phosphoric acid
2) carbonic acid
3) sulfuric acid
4) iodic acid
5) hydrofluoric acid
6) nitrous acid
7) HBr
8) HCN [even though CN¯ is polyatomic, it is named according to the binary rule]
9) HNO3
10) H2SO3
11) H3PO3
12) CH3COOH or HC2H3O2
Here are 10 more:
Name the following acids:
1) H3PO3
2) HClO3
3) H2SO3
4) HBrO3
5) HI
6) CH3COOH
Write the formula for these acids:
7) hydrochloric acid
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8) hydrosulfic acid [this has a twist in it]
9) perchloric acid
10) hydrogen hydroxide
Answers
1) phosphorous acid
2) chloric acid
3) sulfurous acid
4) bromic acid
5) hydroiodic acid (not hydroidiotic acid!)
6) acetic acid
Write the formula for these acids:
7) HCl
8) H2S
9) HClO4
10) HOH (more usually know as H2O or water)
The Nomeclature of Hydrates
Hydrates are substances that include water into their formula.
The water is not actually part of the chemical substance and this is reflected in the way
the formula is written.
Here is the example: CuSO4 . 5 H2O
This formula means that for every one CuSO4 in the piece of this substance you are
holding, there are also five water molecules. No, the substance is not wet, it appears dry.
There are some hydrates that have a wet appearance, but most appear perfectly dry to the
eye and to the touch.
The dot IS NOT a multiplication sign. Remember, this is chemistry, not math.
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Here is the name: copper(II) sulfate pentahydrate. Notice penta meaning five and hydrate
meaning water. You would use this name both when writing the name or speaking it.
That means that when you hear "pentahydrate," you have to know to write the dot and
then the 5 H2O.
Practice Problems
1) Suppose you heard "trihydrate." What would you write?
2) Suppose you heard "octahydrate." What would you write?
3) Name this substance: MgSO4 . 9 H2O
4) Write the formula for: barium chloride dihydrate
Hydrate Problem Answers
1) trihydrate = . 3 H2O
2) octahydrate = . 8 H2O
Now, I know you may have just said three and eight to yourself. That's OK. Just
remember the business with the dot AND putting H2O.
One really silly mistake I've seen is where the kid multiplies everything out. For example,
with trihydrate, the person writes H6O3. So, what they did was take the three which
should be out front and distributed it over the H2O.
Nah! No! Nein! Non!
You get the point.
Right?
3) Name this substance: MgSO4 . 9 H2O
4) Write the formula for: barium chloride dihydrate
Answers:
3) Magnesium sulfate nonahydrate
4) BaCl2 . 2 H2O
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