Naming of Compounds
according to the IUPAC rules
©copyright by James B. Condon (2013) all rights reserved.
©Some of the graphics are supplied by Corel Corporation with their permission.
Use of these materials by others is encouraged provided these notices are not altered.
Naming is broken down into 5 principal classes:
1) binary compounds: a metal with a non-metal
a) with metals of Group 1, 2 and 3*
b) other metals
2) ternary compounds of a metal and a
polyatomic ion.
a) with metals of Group 1, 2 and 3*
b) other metals
3) binary hydrogen compounds
a) as acids in water solution
b) as a gas
4) ternary acids
5) nonmetal-nonmetal compounds
1) Naming of binary metal-nonmetal compounds:
First name the metal and then the nonmetal
(including H) with the ending “ide”.
For metals other than groups 1, 2 and 3*, enter
the oxidation number after the metal name:
Examples for group 1, 2 and 3 metal:
Na2O
CaS
YN
ScH3
= sodium oxide
= calcium sulfide
= yttrium nitride
= scandium hydride
* The actual rule is that for combinations for which
there is only one compound, the oxidation number
1) Naming of binary metal-nonmetal compounds:
First name the metal and then the nonmetal
(including H) with the ending “ide”.
For metals other than groups 1, 2 and 3*, enter
the oxidation number after the metal name:
Examples metal other than group 1, 2 and 3:
FeO
Cu2S
CuO
NiO2
= iron II oxide
= copper I sulfide
= copper II oxide
= nickel IV oxide
* The actual rule is that for combinations for which there is only one
compound, the oxidation number is not written.
Naming of metal-polyatomic ion compounds:
First name the metal with oxidation number
(groups 1, 2 and 3 without) and then the
polyatomic ion.
Look at the polyatomic ion chart. At the top is the
prefixes and suffixes for the columns and on the
left is the root word to use. The prefixes and
suffixes for these compounds (salts) are in the top
row.
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of the ClO 3– ion?
1) Read the root name from the row ClO3– is in.
chlor
2) Read the ion prefix and suffix from the column
label. (Prefix for this is blank.)
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of the ClO 3– ion?
1) Read the root name from the row ClO3– is in.
chlorate
2) Read the ion prefix and suffix from the column
label. (Prefix for this is blank.)
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of NaClO 3?
Do step 1) and 2)
chlorate
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of NaClO 3?
Do step 1) and 2)
sodium chlorate
and put the metal name with it. (Group I - no ON)
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of FePO 2?
phosph
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of FePO 2?
hypophosphite
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of FePO 2?
Iron III hypophosphite
Why III? PO 23– is –3 so Fe must be +3 charge
and therefore has an ON of +3.
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of Sn(ClO 4)2?
Note the parenthesis indicate that ClO4 is a unit,
i.e. a polyatomic ion. Specifically this is then the
polyatomic ion ClO4–.
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of Sn(ClO 4)2?
Each ClO4–. has a single negative charge.
There are two ClO4–s for 2 negative charges
Therefore to balance, the “Sn” must be Sn2+.
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of Sn(ClO 4)2?
Tin II _____?______
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of Sn(ClO 4)2?
Tin II
chlor
Naming of metal-polyatomic ion compounds:
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Example: What is the name of Sn(ClO 4)2?
Tin II perchlorate
Naming of binary hydrogen compounds
that is hydrogen combined with a nonmetal.
As a gas:
Start the name with “hydrogen”. Then add the
name of the non-metal with the “ide” ending as is
done with the metal non-metal compounds.
Examples:
HCl(g)
H2S(g)
HBr(g)
HI(g)
hydrogen chloride
hydrogen sulfide
hydrogen bromide
hydrogen iodide
Naming of binary hydrogen compounds
that is hydrogen combined with a nonmetal.
In solution:
Use the prefix “hydro” and the suffix “ic” and finish
with the word “acid”.
Examples:
HCl(aq)
HI(aq)
H2S(aq)
HBr(aq)
hydrochloric acid
hydroiodic acid
hydrosulfuric acid
hydrobromic acid
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of H 2SO4?
On the chart replace each “–” with a leading “H”.
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of H 2SO4?
sulfur
note italic part is used here.
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of H 2SO4?
sulfuric acid
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of H 2SO2?
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of H 2SO2?
sulfur
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of H 2SO2?
hyposulfurous acid
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of HClO4?
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of HClO4?
chlor
Naming of ternary acids.
(ternary = 3 different atoms)
This comes, again, from the polyatomic ion chart.
ions
a ci d s
c h lo r
b rom
io d
s u l f(u r )
n it r
p h o s p h (o r )
c a rbon
h y p o . . .i t e
h y p o .. .o u s
. . . ite
. . . o us
. . . a te
. . . ic
p e r . . . a te
p er . . . ic
C lO –
B rO –
IO –
S O 22 –
C lO 2–
B r O 2–
IO 2 –
S O 32–
N O 2–
P O 33–
C lO 3 –
B rO 3–
IO 3 –
S O 42 –
N O 3–
P O 43 –
C O 32–
C lO 4–
B rO 4–
IO 4 –
P O 23 –
Use the information in italics for the acids.
prefix root suffix “acid”
Example: What is the name of HClO4?
perchloric acid
Naming of non-metal with non-metals.
1) Name both non-metals
2) Place the number of each in front of the non-metals with
Greek names for the number.
3) Place the ending “ide” on the second non-metal.
4) For the first non-metal, if it has the ending “ine” replace
this with an “o”.
The Greek numbers:
1 - mono
4 - tetra
2 - di
5 - penta
3 - tri
6 - hexa
7 - hepta
8 - octa
9 - ennea
10 - deca
Naming of non-metal with non-metals.
1) Name both non-metals
2) Place the number of each in front of the non-metals with
Greek names for the number.
3) Place the ending “ide” on the second non-metal.
4) For the first non-metal, if it has the ending “ine” replace
this with an “o”.
The Greek numbers:
1 - mono
4 - tetra
2 - di
5 - penta
3 - tri
6 - hexa
7 - hepta
8 - octa
9 - ennea
10 - deca
Example: Name the compound P4O10.
4 - phosphorous 10 - oxygen
Naming of non-metal with non-metals.
1) Name both non-metals
2) Place the number of each in front of the non-metals with
Greek names for the number.
3) Place the ending “ide” on the second non-metal.
4) For the first non-metal, if it has the ending “ine” replace
this with an “o”.
The Greek numbers:
1 - mono
4 - tetra
2 - di
5 - penta
3 - tri
6 - hexa
7 - hepta
8 - octa
9 - ennea
10 - deca
Example: Name the compound P4O10.
4 - phosphorous 10 - oxygen
tetraphosphorous decaoxide
translate and end with
“ide”.
Naming of non-metal with non-metals.
1) Name both non-metals
2) Place the number of each in front of the non-metals with
Greek names for the number.
3) Place the ending “ide” on the second non-metal.
4) For the first non-metal, if it has the ending “ine” replace
this with an “o”.
The Greek numbers:
1 - mono
4 - tetra
2 - di
5 - penta
3 - tri
6 - hexa
7 - hepta
8 - octa
9 - ennea
10 - deca
Example: Name the compound Cl2O3.
2 - chlorine 3 - oxygen
Naming of non-metal with non-metals.
1) Name both non-metals
2) Place the number of each in front of the non-metals with
Greek names for the number.
3) Place the ending “ide” on the second non-metal.
4) For the first non-metal, if it has the ending “ine” replace
this with an “o”.
The Greek numbers:
1 - mono
4 - tetra
2 - di
5 - penta
3 - tri
6 - hexa
7 - hepta
8 - octa
9 - ennea
10 - deca
Example: Name the compound Cl2O3.
2 - chlorine 3 - oxygen Notice that “ine” is
replaced with “o”.
dichloro trioxide
Naming of non-metal with non-metals.
1) Name both non-metals
2) Place the number of each in front of the non-metals with
Greek names for the number.
3) Place the ending “ide” on the second non-metal.
4) For the first non-metal, if it has the ending “ine” replace
this with an “o”.
The Greek numbers:
1 - mono
4 - tetra
2 - di
5 - penta
3 - tri
6 - hexa
7 - hepta
8 - octa
9 - ennea
10 - deca
Example: Name the compound SO3.
1- sulfur 3 - oxygen
Naming of non-metal with non-metals.
1) Name both non-metals
2) Place the number of each in front of the non-metals with
Greek names for the number.
3) Place the ending “ide” on the second non-metal.
4) For the first non-metal, if it has the ending “ine” replace
this with an “o”.
The Greek numbers:
1 - mono
4 - tetra
2 - di
5 - penta
3 - tri
6 - hexa
7 - hepta
8 - octa
9 - ennea
10 - deca
Example: Name the compound SO3.
1- sulfur 3 - oxygen
sulfur trioxide
“mono” is not normally
used - except for:
Naming of non-metal with non-metals.
1) Name both non-metals
2) Place the number of each in front of the non-metals with
Greek names for the number.
3) Place the ending “ide” on the second non-metal.
4) For the first non-metal, if it has the ending “ine” replace
this with an “o”.
The Greek numbers:
1 - mono
4 - tetra
2 - di
5 - penta
3 - tri
6 - hexa
7 - hepta
8 - octa
9 - ennea
10 - deca
Exceptions that use “mono”:
CO - carbon monoxide
NO - nitrogen monoxide
SiO - silicon monoxide
plus a few more that are not too common
The End