Naming with Polyatomic Ions
Naming with Polyatomic Ions
On the bottom of Page 1 of
your Reference Table is a
listing of “Selected
Polyatomic Ions”
Please refer to it.
Naming with Polyatomic Ions
Polyatomic Ions:
- ions made of two or more
atoms
- this charged group is
considered to be a single
ion
- form compounds in the
same manner as the simple
ionic compounds we have
studied
Naming with Polyatomic Ions
Example:
 Ammonium ion
 Formula:
 The +1 charge is spread over
the whole polyatomic
compound, so it is
considered a +1 ion
Naming with Polyatomic Ions
Polyatomic ions can have
different endings than
“ide” depending on how
many oxygen atoms they
contain.
Look at nitrite and nitrate
ions. What is the difference
between formulas?
Naming with Polyatomic Ions
Look at Sulfite and Sulfate.
What is the difference in
their formulas?
What rule can we make
about naming with
different numbers of
oxygen atoms?
Naming with Polyatomic Ions
Practice naming the
following:
Na2SO3 ________________
CaSO4__________________
Write the formula for:
Ammonium Nitrate:
Sodium hypochlorite:
Naming with Polyatomic Ions
Finally, when hydrogen is
present in a polyatomic
ion, we name it.
Example:
HCO3-1 – NOT HOLLISTER
CO.
Correct name:
hydrogen carbonate
HSO4-1 - hydrogen sulfate
Naming Compounds
Containing Transition
Metals
Roman Numerals
• Keep in mind: V = 5 and X = 10
☺Rule: If there is an I before V, it
means SUBTRACT 1 from 5:
5 – 1 = 4 so IV = 4
☺Rule: If there is an I after V, it means
ADD 1 to 5:
5+1=6
so VI = 6
The same goes for X: IX = 9
Roman Numerals
• Roman numerals are used to name ionic
compounds in which the metal has more than one
oxidation state.
• How to count in Roman Numerals:
I =1
V =5
IX = 9
II = 2
VI = 6
X = 10
III = 3
VII = 7
IV = 4
VIII = 8
The following are common transition metal
ions and their oxidation states:
Chromium
+2,+3
Copper
+1,+2
Iron
+2,+3
Lead
+2,+4
Nickel
+2,+3
Tin
+2,+4
Mercury
+1,+2
Naming Transition Elements
Compounds
- Since these metals have a
number of different
oxidation states, they have
to be named differently.
- The oxidation state MUST
appear in the name so we
know which oxidation state
we are dealing with.
Naming Transition Elements
Compounds
• The Roman numerals we
will deal with most are:
I
=
1
II
=
2
III
=
3
IV
=
4
Example: Iron
Fe2+ and Fe+3
FeSO4 is from:
Fe+2 and SO4-2 (sulfate ion)
The name of this compound :
Iron (II) Sulfate
Fe2(SO4)3 is from:
Fe+3 and SO4-2
The name of this compound:
Iron (III) Sulfate
What’s difference does it
make?
• As an example, the
melting point of Iron (II)
Sulfate is 300 deg C
• The melting point of Iron
(III) Sulfate is 400 deg C
• You hemoglobin requires
the Fe+2 ion to carry
oxygen through you body;
Fe+3 won’t work!
Iron (II) ion in Heme
Due to the structure of this molecule, O2
can only “fit” with Fe+2 ions.
“Oddly” Named Elements
Copper
- Symbol Cu
- from the Latin word
Cuprum
- Discovery dates from prehistoric times
Elements with “odd” symbols
• Gold
– Chemical symbol: Au
– From the Latin word “aurum”
Mercury
- Chemical symbol: Hg
- from “hydragyrum”
- meaning “liquid silver”
Elements with “odd” symbols
• Silver
– Chemical symbol: Ag
– From the Latin word
“argentum”
Lead
- from the Latin “plumbum”
Elements with “odd” symbols
• Iron
– Chemical Symbol: Fe
– from the Latin “Ferrum”
Tin
- Chemical Symbol: Sn
- from the Latin “Stannum”
Elements with “odd” symbols
• Sodium
– Chemical Symbol: Na
– From the Latin “natrium”
• Tungsten
• Chemical Symbol: W
• From the word “Wolfram”
which is the ore it is found in