Here we’ll go over a couple of examples of naming simple ionic compounds
containing 2 elements.
Binary Compounds
-Compounds containing only 2
elements
The prefix “bi” means 2, so compounds containing only two elements are called
binary compounds.
Binary Compounds
-Compounds containing only 2
elements
Binary Ionic Compounds
-Contain a metal and a non-metal
Binary Ionic compounds are made up of a metal and a non-metal
Metals
Non -Metals
This Periodic Table has a staircase drawn with a black line. The elements to the left
of the staircase are metals and those to the right are non-metals.
Charge on the
most common
ion of this
element
When an atom of a metal loses one or more electrons, it forms a positive ion. It is
the ions of metals that form ionic compounds.
Charge on the
most common
ion of this
element
The little number on the top right of an element’s box is the charge of the most common ion of
the element. We see that magnesium has only one number so it only has 1 common charge.
Charges on the
most common
ions of this
element
Some metals, like iron form ions with more than one common charge.
Charges on the
most common
ions of this
element
One common ion of iron has a positive 3 charge and the other common ion has a positive
2 charge.
Metals with Only One
Common Charge
At this point, we’ll discuss only compounds of metals with a single charge. These are shaded in
green here. We’ll discuss compounds formed by the other metals in a later video.
Rules for Naming Binary Ionic
Compounds in which the Metal
has Only One Charge
1. Always name the metal first.
2. Name the non-metal second.
3. Change the ending of the non-
Here we’ll go over the basic rules for naming a binary, or 2 element, ionic compound in which
the metal present has only one possible charge.
Rules for Naming Binary Ionic
Compounds in which the Metal
Compound
has Only One Charge names
are all
in lower case
1. Always name the metal first.
2. Name the non-metal second.
3. Change the ending of the nonmetal so it ends in -ide.
Just a general comment about compound names. Compound names are always written in
lower case and not capitalized, unless they are at the beginning of a sentence.
Rules for Naming Binary Ionic
Compounds in which the Metal
Compound
has Only One Charge names
are all
in lower case
1. Always name the metal first.
2. Name the non-metal second.
3. Change the ending of the nonmetal so it ends in -ide.
Always name the metal first. The metal name is not changed in any way. If it’s a metal with only
one possible charge, we don’t need to worry about any numbers that are in a given formula.
Rules for Naming Binary Ionic
Compounds in which the Metal
Compound
has Only One Charge names
are all
in lower case
1. Always name the metal first.
2. Name the non-metal second.
3. Change the ending of the nonmetal so it ends in -ide.
The name of the non-metal always comes second
Rules for Naming Binary Ionic
Compounds in which the Compound
Metal
are all
has Only One Charge innames
lower case
1. Always name the metal first.
2. Name the non-metal second.
3. Change the ending of the non-
The name of the non-metal must be changed so that it ends in the letters I D E. For example
chlorine is changed to chloride and oxygen is changed to oxide.
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
A compound is made up of the elements potassium and
sulphur. Name this compound.
potassium sulph
ur
Here’s an example question. We’re told that a compound is made up of the
elements potassium and sulphur and we’re asked to name this compound.
Metals
Non -Metals
A compound is made up of the elements potassium and
sulphur. Name this compound.
We start by locating potassium and sulphur on the periodic table. We see that
potassium is a metal and sulphur is a non-metal, so this is an ionic compound.
One possible charge
A compound is made up of the elements potassium and
sulphur. Name this compound.
Looking more closely at potassium, we see that it has only one possible charge.
Therefore, we can use the simple method of naming outlined here.
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
potassium
sulph
u
r
A compound is made up of the elements potassium and
sulphur. Name this compound.
We write the metal name first, potassium, the same way it is spelled on the
periodic table. Notice we did not capitalize it.
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
potassium
sulph
u
r
A compound is made up of the elements potassium and
sulphur. Name this compound.
Now we note that the second element, the non-metal, is sulphur
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
potassium
sulph
u
r
A compound is made up of the elements potassium and
sulphur. Name this compound.
The third step says, we must change the non-metal name so that it ends in the
letters IDE. Notice it now ends in the letters U-R
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
potassium
sulph
u
ide
r
A compound is made up of the elements potassium and
sulphur. Name this compound.
So we drop the ending “ur” and replace it with “ide”.
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
potassium
sulph
ide
A compound is made up of the elements potassium and
sulphur. Name this compound.
Giving us the name potassium sulphide
Name
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
potassium
ide
sulph
or
potassium sulf
ide
Name
A compound is made up of the elements potassium and
sulphur. Name this compound.
In many places sulphur is spelled with an “f” rather than a “ph”, so the spelling
s-u-l-f-i-d-e is also considered correct in the name potassium sulphide.
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
The formula for a compound is Cd3P2. Name this
compound.
potassium sulph
ur
Here’s another example question. We’re told that the formula for a compound is
Cd3P2 and we’re asked to name this compound.
Metals
Non -Metals
The formula for a compound is Cd3P2. Name this
compound.
We start by locating Cd and P on the periodic table. We see that they are the metal
cadmium and the non-metal phosphorus, so this is an ionic compound.
One possible charge
The formula for a compound is Cd3P2. Name this
compound.
Looking more closely at cadmiun, we see that it has only one possible charge.
Therefore, we can use the simple method of naming outlined here.
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
cadmium phosph
orous
The formula for a compound is Cd3P2. Name this compound.
We write the name of the metal first, unchanged. It is cadmium
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
cadmium phosph
orus
The formula for a compound is Cd3P2. Name this compound.
Next, we note the name of the non-metal, which is phosphorus
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
cadmium phosph
orus
The formula for a compound is Cd3P2. Name this compound.
However, rule number 3 tells us that the name of the non-metal must end in the
letters I-D-E.
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
cadmium phosph
ide
orus
The formula for a compound is Cd3P2. Name this compound.
So we take the ending o-r-u-s (click) are we replace it with i-d-e
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
cadmium phosph
ide
Name
The formula for a compound is Cd3P2. Name this compound.
Giving us the correct name for this compound, cadmium phosphide.
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
Cd3P2
subscripts have
no effect on the
name
subscripts
cadmium phosph
ide
The formula for a compound is Cd3P2. Name this compound.
Notice that the formula in this example has numbered subscripts 3 and 2
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
Cd3P2
subscripts have
no effect on the
name
subscripts
cadmium phosph
ide
The formula for a compound is Cd3P2. Name this compound.
But because the metal in this compound, cadmium only has one possible charge
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
Cd3P2
subscripts have
no effect on the
name
subscripts
cadmium phosph
The formula for a compound is Cd3P2. Name this compound.
The subscripts have no effect on the name.
ide
1.
2.
3.
Always name the metal first.
Name the non-metal second.
Change the ending of the non-metal so it ends in -ide.
Cd3P2
subscripts have
no effect on the
name
subscripts
cadmium phosph
The formula for a compound is Cd3P2. Name this compound.
And the name is simply cadmium phosphide
ide