1. Oxides Tutorial
The Oxides are constituted by:
A metal + Oxygen, in where: The metal works with positive
valence and oxygen, with valence -2.
When being united both elements, cross their valences, in
such form that the valence of the first element, stays vice
versa as the subscript of the second:
Example: Na+1 and O-2, if they are united to form
2. oxide, interchanges their valences as you can see:
Na+1
O-2
Na2O
Like in algebra, number one is not written, is implicit
with the symbol of the element.
In the same way, you can form oxides with other metals:
Al+3
y O-2
Al2O3
Ag+1
y O-2
Ag2O
Elements Chemical Formula
3. We must consider that the chemical formulas, like
the fraction in mathematics can be simplified, as long as
both constituent elements can do it in simultaneous form,
for example:
Elements intermediate Final
Formula formula
Mg+2
y O-2
Mg2O2 MgO
Pb+4
y O-2
Pb2O4 PbO2
The final formula is the correct.only
4. In order to name oxides, we have a nomenclature rule:
* The name Oxide is given to __________ ________
metal name valence of the
metal in roman
number
(With exception of metals with unique valence, the Roman number is not placed.)
Fe2O3 Iron oxide III.
K2O Potasium oxide .
We only must have care that with formulas already
simplified, the oxygen always works with valence -2 .
examples:
example:
5. NiO ------ since the 2 of oxygen does not appear like
subscript of nickel, this indicates that the formula is
simplified and also the nickel works then the valence 2,
but positive, is for that reason that does not appear either.
Reason why the correct name will be:
SnO2 ------ Again does not appear the 2 of oxygen as
subscript of tin, which suggests that its formula is
simplified and also tin was reduced to half, so its valence
is +4, then, the correct name will be:
As you see, although the formula is simplified, in
the name of the compound, is due to place its valence.
Nickel oxyde II.
Tin oxide IV.
6. Also we will see the form to obtain an oxide by means
of chemical reactions and their balance by rough estimate.
The general reaction of obtaining is as it follows:
If we observe the reaction, we realize that which
oxygen has 2 as subscript, which does not have to do with its
valence.
Oxygen, as well as the halogenous, the hydrogen, nitrogen,
etc., when they are single (without combining), are so unstable
that they require to be with an identical atom, and are called
diatomic molecules.
Metal + O2 oxide
7. Next, we will complete the reaction step by step and it
will be balanced by rough estimate.
Cu+1
+ O2 _____________
Step 1: The reaction is completed forming the correct
oxide (valencies interchange solely, as already we had done
it, is not taken into account the subscript from oxygen in this
first part).
Cu+1
+ O2 Cu2O
Example :
8. Step 2: The reaction is balanced, now taking into
account all the moles present from each element (subscripts).
4Cu+1
+ O2 2Cu2O
The same process is followed exactly for any metal.
Now make the next exercises:
Write down the correct formula to the following oxides:
1)Iron oxide II. 2) Chromium oxide III.
3) Copper oxide I. 4) Mercury oxide II.
5) Bismuth oxide V.
9. II. Write the correct name of following oxides:
1) PtO2 4) Au2O3
2) Bi2O3 5) MnO
3) Li2O
III. Complete and it balance the following reactions:
1) Ag + O2
2) Ca + O2
3) Co+3
+ O2
11. NAMES AND NUMBERS OF OXIDATION OF
POLIATOMICS IONS
NAME OF THE
OXYACID
(PREFIX___SUFIX)
NUMBER OF
OXIDATION
-1
NUMBER OF
OXIDATION -2
NUMBER OF
OXIDATION
-3
NAME OF SALT
(PREFIX___SUFIX)
HIPO___OSE ClO BrO IO SO2 SeO2
TeO2
HIPO___ITE
___OSE
ClO2 BrO2
IO2 NO2
SO3 SeO3
Te03 CO2
MnO3
AsO3 SbO3
PO3 ____ ITE
____ICE
ClO3 BrO3
IO3 NO3
SO4 SeO4
TeO4 CO3
SiO3 MnO4
CrO4
AsO4 SbO4
PO4 BO3 ____ ATE
PER___IC ClO4 BrO4
IO4 MnO4
PER___ATE
