Nomenclature
Scientific Naming System
What is the difference
between an element
and a compound?
Definitions
 Elements cannot be broken down by physical or chemical
changes.
 Compounds are composed of 2 or more elements that can be
broken down by chemical change.
 What type of matter can be broken down by physical
changes?
Ions
 Ions are elements with a charge. The reference table lists




these charges for each element.
If the element is positive, it is called a cation.
Cations are named the same as the element.
(Example: Ca=Calcium atom / Ca+2=Calcium ion)
If the element in negative, it is called an anion.
Anions are named ending with “-ide”
(Example: N=Nitrogen atom / N-3 = Nitride ion)
You try:
Mg+2
+
K
-2
O
F
+
Li
I-
Binary Compounds
Binary Compounds consist of only two of elements. To
name: write the complete name of the first element.
The second element should then be named, ending in “ide.”
 NaCl
 KI
 MgCl2
 Ca3N2
sodium chloride
potassium iodide
magnesium chloride
calcium nitride
You try…
Li3P
Al2S3
SrBr2
Rb2O
BaSe
CsI
Criss-cross Rule
To write a formula, write the two ions separately showing their
charges. Charges are on the periodic table. Then, swap the
two numbers and drop the sign:
Calcium nitride:Ca2+
Ca3N2
Lithium oxide: Li+
O-2
Li2O
N-3
Notice, we don’t
write ones!
Problem:
 FeCl2 and FeCl3 are different compounds but
seem to have the same name. How can we name
them different?
 FeCl2 is iron (II) chloride
FeCl3 is iron (III)
chloride.
 What do the roman numerals represent?
Transition Metals and nonmetals
 Transition Metals are in the
middle group of the
periodic table.
 Nonmetals are on the right
side of the staircase.
 They have multiple charges
or oxidation numbers and
so you must show which
charge you are using with
roman numerals:
I
II
III
IV
V
VI
VII
Try these…
FeCl2
CuF
ZnO
N2O3
SO4
PCl3
CH4
Careful:
This rule doesn’t ALWAYS work for
cations. Find the anion’s charge
and equalize that with the cation’s
charge as a check.
Try these…
 Potassium iodide
 Magnesium chloride
 Aluminum sulfide
 Hydrogen oxide
 Barium selenide
 Cesium phosphide
 Strontium phosphide
 Copper (II) flouride
 Iron (III) telluride
Tertiary Compounds
 When compounds have more than 2 elements, it
contains a polyatomic ion.
 Polyatomic ion are a group of 2 or more atoms
that are bonded very strongly and act as one ion.
AgNO3
silver nitrate
Polyatomic ions
 You are given a list of polyatomic ions. Naming compounds
with these ions are easy once you familiarize yourself with
the list.
 CaCO3
 LiClO2
 NaOH
 (NH4)3PO4
calcium carbonate
lithium chlorite
sodium hydroxide
ammonium phosphate
You try…
 K2SO4
 CsNO2
 Ba(SCN)2
 SrClO3
 Al(HCO3)3
 RbCN
Try These…
Name:
Fe(SCN)2
CoCl3
NiBr2
CuO
MnI4
Ag2S
Write the formula:
Nickel (III) Nitride
Manganese (II) sulfite
Zinc sulfate
Titanium (II) carbonate
Gold (III) oxide
Iron (III) Chloride
Game
http://www.sciencegeek.net/APchemistry/APtaters/director
y.shtml
Covalent Compounds
 In some cases, binary covalent compounds (compounds with
nonmetals only) are named using prefixes and end in “-ide.” The
prefixes used are listed below.
1
2
3
4
5
6
7
8
9
monoditritetrapentahexaheptaoctnon-
Name or write the formula:
NO
H 2O
PCl5
Cl2O7
Carbon tetrachloride
Phosphorous tribromide
Silicon dioxide