Formula writing for ionic compounds using the Stock system
Terms you need to know:
Ion – a charged atomic or molecular particle.
Cation – a positively charged atomic or molecular particle (lost electrons or has more protons than electrons).
Anion – a negatively charged atomic or molecular particle (gained electrons or has more electrons than protons).
Monoatomic – a particle that is made of a single atom or started as a single atom that lost of gained electrons.
Polyatomic – a particle that is made of covalently bonded atomic particles.
-ide suffix – a word ending that tells you that 1) the particle is a monoatomic ion, 2) is a polyatomic ion that
DOES NOT contain oxygen, or 3) is the last atom written in the formula of a covalent compound.
-ate suffix – a word ending that tells you that the polyatomic anion formula contains oxygen in the formula and
has one more oxygen than a similarly named particle with an –ite suffix.
-ite suffix – a word ending that tells you that the polyatomic anion formula contains oxygen in the formula and
has one less oxygen than a similarly named particle with an –ate suffix.
Oxidation number – hypothetical numbers assigned to an individual atom or ion present in a substance using a
set of rules. Oxidation numbers (or oxidation states as they are also called) can be positive, negative, or
zero. Oxidation numbers are always reported for one individual atom or ion and not for groups of atoms or
ions. The oxidation number of a monoatomic ion is equal to the charge of the monatomic ion
How do we name compounds when the metal
element has more than one charge?
Some metals have more then one oxidation number
when naming a compound these must be identified.
Roman numerals are shown after the cation in
parenthesis( ) to indicate the oxidation number.
To determine what the oxidation number is, you
must use the anion (negative ion) to determine what
positive oxidation number is.
Example- Pb(NO3)4 write the name "lead nitrate".
Since lead has more than one oxidation state we
must figure out which lead we have. Since each
nitrate (4 of them) has a 1- charge, the Pb must be
So our roman numeral will be (IV).
The Stock System
History- The type of naming you will learn about
is called the Stock system or Stock's system. It was
designed by Alfred Stock (1876-1946), a German
chemist and first published in 1919. In his own
words, he considered the system to be "simple,
clear, immediately intelligible, capable of the most
general application."
In 1924, a German commission recommended
Stock's system be adopted with some changes. For
example, FeCl2, which would have been named
iron(2)-chloride according to Stock's original idea,
became iron(II) chloride in the revised proposal. In
1934, Stock approved of the Roman numerals, but
felt it better to keep the hyphen and drop the
parenthesis. This suggestion has not been followed,
but the Stock system remains in use world-wide.
Pb(NO3)4 is named "lead(IV) nitrate"
and
the
4+.
Complete the table below:
Formula
Name
Name
FeCl2
tin(IV) chloride
CoBr3
iron(III) phosphide
MnO2
mercury(I) sulfide
NiBr2
lead(II) oxide
HgO
gold(I) iodide
CuF2
tin(IV) sulfide
CuI
iron(III) bromide
SnBr2
chromium(III) oxide
Au3P
cobalt(II) sulfide
Cr2S3
manganese(II) iodide
NiBr
nickel(II) sulfide
FeS
lead(IV) oxide
PbCl4
manganese(V) oxide
Formula