What is Metal Oxide Properties: Let us know about Metal Oxide Properties. Metal oxides are those inorganic compounds formed by metallic cations and oxygen. They usually consist of a large number of ionic solids, in which the oxide anion (O 2 ) interacts electrostatically with the M species + .
M + It is any cation that is derived from a pure metal: from alkaline and transition metals, with the exception of some noble metals (such as gold, platinum and palladium), for the heavy elements of block P of the periodic table ( lead and like bismuth).
The upper image shows an iron surface covered with a reddish crust. These “crusts” are known as rust or corrosion, which in turn represent a visual test of the oxidation of the metal due to the conditions of its environment. Chemically, rust is a hydrated mixture of iron oxides (III).
Why does the oxidation of a metal result in corrosion of its surface? This is due to the inclusion of oxygen within the crystal structure of the metal.
When this happens, the amount of metal increases and the basic interactions are weakened, causing the solid to break up. In addition, these cracks allow more oxygen molecules to penetrate the inner metal layers, eating up the entire piece from within.
However, this process occurs at different speeds and depends on the nature of the metal (its reactivity) and the physical conditions around it. Therefore, there are factors that accelerate or slow down the oxidation of the metal; Two of them are the presence of moisture and pH.
Why? Because the oxidation of a metal implies an electron transfer to produce a metal oxide. These “travel” from one chemical species to another as long as the medium facilitates it, either by the presence of ions (H + , Na + , Mg 2+ , chlorine – , etc.), which modify the pH, or Water molecules that provide the means of transport.
Analytically, the tendency of a metal to form related oxides is reflected in its reduction potential, which describes which metals react faster than another.
For example, gold has a much greater reduction than iron, which is why it shines with its luster without its oxides.
Properties of non-metal oxide
To know about Metal Oxide Properties, now know Properties of non-metal oxides. The properties of metal oxides vary according to the metal and how it interacts with the ion O 2- . This emphasizes that some oxides have a higher density or solubility than water. However, all have the same character as the metal, which is essentially reflected in its originality.
In other words: they are also known as basic anhydrides or basic oxides.
basicity
The basicity of metal oxides can be experimentally checked using an acid-base indicator. How? Adding a small piece of oxide to the aqueous solution with some dissolved indicator; It could be the liquefied juice of purple cabbage.
Then depending on the pH of the range of colors, the oxide will turn the sap blue to the same color as the original pH (with values between 8 and 10). This is because the dissolved part of the oxide releases OH ions – in the environment, these are responsible for changes in pH.
Thus, for MO oxide dissolved in water, it turns into metal hydroxide (“hydrated oxide”) according to the following chemical equations:
Mo + H 2 O => M (OH) 2
M (OH) 2 <=> M 2+ + 2OH –
The second equation is the solubility equilibrium of hydroxide M(OH) 2 . Note that the metal has a 2+ charge, which also means that it has a value of +2. The valency of a metal is directly related to its tendency to gain electrons.
Thus, the higher the positivity, the higher its acidity. In the case that the valence of M was +7, then the oxide of M 2 O 7 would be acidic and not basic.
amphoterism
To know about Metal Oxide Properties, now you know amphoterism. Metal oxides are basic, however, not all have the same metallic character. How to know? Detection of metal M in the periodic table. The more it is to the left of it, and the less time, the more metallic it will be and therefore the greater its core.
At the boundary between basic and acid oxides (non-metal oxides) are amphoteric oxides. The term ‘amphoteric’ here means that the oxide acts as both a base and an acid, similar in aqueous solution, which can form hydroxides or the aqueous compound M(OH). 2 ) 6 2+ .
The coordination of the aqueous complex is nothing more than the n water molecule with the metal center M for the M complex (OH 2 ) 6 2+ , the metal M 2+ It is surrounded by six water molecules, and is called a hydrated cage. can be considered as. Intense colors appear in many of these complexes, such as those observed for copper and cobalt.
Glossary
How are metal oxides named? There are three ways to do this: Traditional, Systematic and Stock.
traditional nomenclature
In order to correctly designate metal oxides according to the rules governed by IUPAC, it is necessary to know the possible values of metal M. The name of the largest (most positive) metal is assigned the suffix -, while the minor, the prefix -jo.
Example: Given the values +2 and +4 of metal M, its corresponding oxides are MO and MO 2 . If M was lead, Pb, then PbO oxide would be plumb bear, and PbO 2 oxide would be plumb ico . If the metal has only one valence, its oxide is named with the suffix -xo. So, Na 2 or it is sodium oxide.
On the other hand, the hypo- and counter- prefixes are added when three or four values are available for the metal. In this way, M.N. 2 O 7 This is the oxide per Mangan ico , because Mn has a valence +7, which is the highest of all.
However, this type of nomenclature presents some difficulties and is used sparingly.
systematic nomenclature
To know about Metal Oxide Properties, now know systematic nomenclature. This considers the number of M atoms and oxygen that make up the chemical formula of the oxide. From them, it is assigned the corresponding prefix mono-, di-, tri-, tetra-, etc.
Taking three recent metal oxides as an example, PbO is lead monoxide; PbO 2 lead dioxide; And Na 2 or disodium monoxide. As for the case of corrosion, Fe 2 O 3 , its related name is dihydro’s trioxide.
stock nomenclature
Unlike the other two nomenclatures, the valency of the metal is more important in this. Specified by Roman numerals in parentheses: (I), (II), (III), (IV), etc. Metal oxides are then designated as metal oxides (n).
Applying stock nomenclature to the previous examples we have:
-PbO: lead oxide (II).
-PBO 2 : Lead Oxide (IV).
-Na 2 O: sodium oxide. Since it has a unique valence of +1, it is not specified.
-Religion 2 O 3 : Iron oxide (III).
-Mn 2 O 7 : Manganese oxide (VII).
Calculating the number of valence
But, if you don’t have a periodic table with valences, how can you determine them? For this we must remember that the anion O2 contributes two negative charges to the metallic oxide. These negative charges must be neutralized with the positive ones of the metal, following the principle of neutrality.
Therefore, if the number of oxygens is known from the chemical formula, the valency of the metal can be determined algebraically, so that the sum of the charges becomes zero.
The Mn2O7 has seven oxygens, so its negative charge is equal to 7x(-2) = -14 . To neutralize the negative charge of -14, manganese must provide +14 (14-14 = 0). Putting the mathematical equation is then:
2X – 14 = 0
2 comes from the fact that there are two manganese atoms. Solving and Clearing X, Valency of Metals:
x = 14/2 = 7
That is to say, the value of each Mn is +7.
How are they made?
Humidity and pH directly affect the oxidation of metals into their respective oxides. The presence of CO 2 , the acid oxide, can be sufficiently dissolved in water that covers part of the metal to accelerate the incorporation of oxygen in the ionic form for the crystal structure of the metal.
This reaction can also be accelerated with an increase in temperature, especially when it is desired to obtain the oxide in a short time.
direct reaction of metal with oxygen
Metal oxides form as a product of the reaction between the metal and the surrounding oxygen. This can be represented with the chemical equation given below:
2M(s) + O2 ( g) => 2MO(s)
This reaction is slow, because oxygen has a strong double O = O bond and electronic transfer between it and the metal is inefficient.
However, it accelerates significantly with increase in temperature and surface area. This is due to the fact that the energy needed to break the O=O double bond is provided, and as there is a larger area, the oxygen moves evenly across the metal, colliding with the metal atoms at the same time. Is..
The higher the amount of oxygen reactor for the metal, the higher the valence or oxidation number. Why? Because oxygen is stripping more and more electrons from the metal until it reaches the highest oxidation number.
This can be seen for copper, for example. When a piece of metallic copper reacts with a limited amount of oxygen to form Cu 2 O (copper oxide (I), cupre oxide or dicober monoxide):
4Cu(s) + O 2 (g) + Q (heat) => 2Cu 2 O (s) (red solid)
But when it reacts in equal amounts, CuO (copper oxide (II), cupric oxide or copper monoxide) is obtained:
2Cu(s) + O 2 (g) + Q (heat) => 2CO(s) (solid black)
Reaction of metal salts with oxygen
Metal oxides can be formed through thermal decomposition. For this to be possible, one or two small molecules must be released from the starting compound (a salt or a hydroxide).
M (OH) 2 + Q => Mo + H 2 O
MCO 3 + Cu => Mo + CO 2
2M (No. 3 ) 2 + Q => Mo + 4. NO 2 + O 2
Note that H 2 O, CO 2 , NO 2 and O 2 are the released molecules.
Applications
Due to the rich composition of metals in the Earth’s crust and oxygen in the atmosphere, metal oxides are found in many mineral sources, from which a solid basis for the creation of new materials can be obtained.
Each metal oxide has very specific uses, from nutrition (ZnO and MgO) to cement additives (CaO), or simply as inorganic pigments (Cr). 2 O 3 ).
Some oxides are so dense that controlled growth of their layers can protect an alloy or metal from further oxidation. Even studies have shown that the protective layer is oxidized as if it were a liquid that covers all cracks or superficial defects of the metal.
Metal oxides can adopt attractive structures, either as nanoparticles or as large polymeric aggregates.
This fact makes them a subject of study for the synthesis of intelligent materials, due to its large surface area, which are used to design devices that respond to minimal physical stimuli.
Similarly, metal oxides are raw materials for many technological applications, from mirrors and ceramics with unique properties to electronic components, to solar panels.
Example
iron oxide
2Fe ( S) + O 2 (g) => 2FeO (s) Iron Oxide (II).
6 FeO (o) + O 2 (g) => 2Fe 3 O 4 (s) magnetic iron oxide.
Astha 3 O 4 , also known as magnetite, is a compound oxide; This means that it contains a solid mixture of FeO and Fe 2 O 3 .
4Fe 3 O 4 (s) + O 2 (g) => 6Fe 2 O 3 (s) iron oxide (III).
alkaline and alkaline earth oxides
Both alkaline and alkaline earth metals have a single oxidation number, so their oxides are more “simple”:
-Na 2 O: sodium oxide.
-Li 2 O: Lithium oxide.
-K 2 O: potassium oxide.
-CaO: calcium oxide.
-MgO: Magnesium Oxide.
-BeO: Beryllium oxide (which is an amphoteric oxide)
Group IIIA oxide (13)
Elements of group IIIA (13) can form oxides only with the oxidation number +3. Thus, they have a chemical formula M 2 O 3 and the following are its oxides:
-Co 2 O 3 : aluminum oxide.
-Ga 2 O 3 : Gallium Oxide.
-in 2 O 3 : indium oxide.
And finally
-tl 2 O 3 : thallium oxide.
