Oxide

Oxide . Binary oxygen compound with another element. The oxides have been prepared basically with all the elements, except the noble gases. Often, different oxides of a given element can be prepared. A certain number of them exist in the Earth’s crust and in the atmosphere : silicon dioxide (SiO2) in quartz ; aluminum oxide (A12O3) in the corundum ; iron oxide (Fe2O3) in hematite ; carbon dioxide (CO2) in the form of a gas; and water (H2O).

Summary

[ hide ]

  • 1 Training process
  • 2 Physical properties of oxides
  • 3 Classification of oxides
  • 4 Chemical nomenclature
    • 1 Names
    • 2 Non-metallic oxides
    • 3 Metal oxides
    • 4 Other criteria
      • 4.1 Systematics
      • 4.2 Stock
      • 4.3 Traditional
    • 5 Chemical notation
      • 1 Formulas
    • 6 Applications of oxides
    • 7 Specific applications
    • 8 Sources

Training process

Most of the elements react with oxygen under appropriate conditions of pressure and temperature , and various oxides can be prepared directly. Almost all metals react with oxygen slowly at room temperature since an oxide film is formed first that protects the metal. The oxides of alkali and alkaline earth metals, except for beryllium and magnesium , are porous when they form on the metal surface and provide little protection against oxidation, even at room temperature. the goldIt is exceptional for its resistance to oxygen, and its oxide (Au2O3) must be prepared by indirect methods. The other noble metals, although usually resistant to oxygen, react at high temperatures to form gaseous oxides.

Physical properties of oxides

The physical properties of oxides are extremely varied. Some are gaseous at room temperature, like carbon dioxide ; others, on the other hand, are solids with high melting temperatures , such as magnesium and calcium oxides, and others are liquids at room temperature, such as water.

The solubility and color vary from one oxide to another.

Classification of oxides

  • Basic oxides: They are formed by metals. The metal present in its formula can have an electric charge of +1 and +2, that is, it has an ionic character. Examples: Na 2 O ( sodium oxide ), BaO ( barium oxide ).
  • Neutral oxides: They are composed of non-metals. They do not react with water, acid or base, due to the covalent bond that unites their components; hence the reason for being called inert oxides. Examples: dinitrogen monoxide (N 2 O) and carbon monoxide (CO).
  • Acid oxides: Also known as acid anhydrides, they are formed by non-metals and have a covalent character. In the presence of water, they produce acids and in the presence of bases, it produces salt and water. Example: CO 2 ( carbon dioxide or carbon gas) and SO 2 ( sulfur dioxide )
  • Double or mixed oxides: The combination of two oxides of the same element, gives rise to this type of oxide. Example: magnetite (Fe 2 O 4 ), union of iron (Fe) and oxygen (O) oxides .
  • Amphoteric oxides: They present ambiguity, in the presence of an acid they behave like basic oxides and in the presence of a base, like acidic oxides. Examples: aluminum oxide (Al 2 O 3 ) and zinc oxide (ZnO).
  • Peroxides: Compounds that have in their formula the group (O 2 ) 2- . The most common peroxides are formed by hydrogen , alkali metals and alkaline earth metals. Examples: hydrogen peroxide (H 2 O) and sodium peroxide (Na 2 O 2 ).

Chemical nomenclature

Names

Oxides can be named according to two criteria:

  • Taking into account the number of atoms represented in the chemical formula. This is preferably used to name the non-metallic oxides.
  • Expressing the oxidation number of the chemical element, joined to the oxygenin the oxide when it is variable. This is preferably used to name the metal oxides.

Non-metallic oxides

To name the non-metallic oxides the prefixes mono , di , tri , tetra , etc. are used, according to the number of atoms of each element in the chemical formula. These prefixes are placed before the generic word oxide and the name of the non-metallic element, the latter being preceded by the preposition “de”. The prefix “mono”, before the name of the nonmetal, is usually omitted.

Examples:

Metal oxides

To name metallic oxides the generic word oxide is written, followed by the preposition “of” and then the name of the metallic element. When the metallic element has more than one oxidation number, a Roman number is placed in parentheses, after the name, indicating its value.

Other criteria

There are authors who use other criteria to name oxides and for this they use 3 nomenclatures: traditional, systematic and stock.

Systematic

Oxides, both acidic and basic, are named by writing in front of the word oxide and the name of the element, some prefixes that indicate the number of atoms of the same element that it has in that molecule .

The nomenclature applies to the formula that is already simplified. The prefix “mono” can be removed; This means that if an element does not have a prefix, only one atom of that element intervenes in the same formula.

Examples: As 2 S 3 ( diarsenic trisulfide ); PF 5 ( phosphorous pentafluoride ).

Stock

Oxides, both acidic and basic, are named by the words “oxide of”, followed by the name of the element and a parenthesis where the valence of the element is put in Roman numerals, as it was at the beginning without simplifying. If an element has only one valence, no parentheses are put.

Examples: Fe 2 O 3 ( iron oxide III); SO 3 ( sulfur oxide (VI) ; FeO ( iron oxide II); Na 2 O ( sodium oxide ).

Traditional

For the basic oxides:

  • If the metal with which it is combined has a single valence, they are named with the words oxide of, and the name of the metal with which it is combined. Examples: CaO ( calcium oxide ); Na 2 O ( sodium oxide ).
  • If the metal with which it is combined has two valences, it is put as in a valence but the name of the metal ends in bear when it acts with the lowest valence and in ico when it acts with the highest valence and the prefix is ​​removed ” of”.

Examples: FeO ( ferrous oxide , iron in this case has valence 2 and is simplified); Fe 2 O 3 ( ferric oxide , iron in this case has valence 3).

For acidic oxides:

  • If the nonmetal with which it is combined has a single valence, they are named with the words oxide of, and the name of the metal with which it is combined finished in ico . Examples: B 2 O 3 ( boric oxide .
  • If the nonmetal with which it is combined has two or more valences, the following endings are named:

Examples: Br 2 </ sub <sub O 5 ( bromic oxide ); Cl 2 O 7 (bromic oxide).

Chemical notation

Formulas

When writing the chemical formula for non-metallic oxides, write the symbol for the non-metallic element first and then the oxygen symbol . Subscripts are placed according to the number of atoms of each chemical element.

To write the chemical formula of metal oxides, you must know the oxidation number of the metallic element and remember that the oxygen number is always 2-. With these data, proceed as follows:

This procedure is also applicable to non-metallic oxides.

Applications of oxides

Since ancient times, man had been painting on the rocks and the walls of the caves he inhabited, for which he used aqueous or oleaginous suspensions of colored substances. Many of these substances were oxides. The use of oxides (natural in most cases) for the manufacture of paints, continues to this day. Some of the oxides used are:

  • ZnO —— ZincWhite, China White, Snow White, Philosophical Wool, Spartaline, Pomfolix.
  • TiO 2——— Titanium White
  • Sb 23 ——- Antimony white
  • Pb 34 ——– Minium, Paris Red , Cinnabar of Saturn.
  • Cr 23 ——– Chromium oxide green
  • Co 34 ——– Cobalt Black
  • Cu 2O —— Cuprous Oxide, Red Copper, Cuprite
  • Faith 23 ——— Red Hematite, Minium Iron , Magisterium of Mars, Moreno de Van Dick, Almagre, Calcotar, Saffron from Mars
  • Faith 34 ——— Magnetite, Lemery Saffron

Specific applications

  • The silica(quartz), in its various varieties (agate, amethyst, onyx, rock crystal, etc.), is used for ornamental purposes. Siliceous sands are the raw material for glass manufacturing . Quartz is used for the manufacture of construction materials (cement, concrete, etc.).
  • Arsenicoxides are used in the glass industry. They are also used for the preparation of poisons, dyes and agrochemicals. In medicine, small doses are given for certain treatments.
  • The oxide red copper(cuprite) is added to the glasses to give red coloration.
  • The magnesium oxide(periclase, calcined magnesia) serves for the preparation of basic carbonates of magnesium and resistant mortars water. Its majority use is in the manufacture of refractory materials. They are used in the manufacture of fertilizers and in the preparation of medicines against heartburn. It is used as an antidote for many types of poisoning.
  • The natural zinc oxide(zincite) is used as a synthetic product, both for the manufacture of paints and dyes, and for the preparation of antiseptic ointments and cosmetic products.
  • Aluminumoxides , in addition to being aluminum ore, are used as gems ( sapphire , ruby ). Emery (a variety of corundum) is used to work hard metals and alloys. In the ceramic industry, alumina balls are used for grinding quartz and feldspars.
  • Leadoxides are rare minerals and therefore those obtained by synthesis are used. They are used in the manufacture of glass (quality glass), in the manufacture of lead salts and various colorants.
  • Bismuthoxides are used as colorants in paints and enamels. They also serve for the manufacture of optical quality glasses.
  • Manganeseoxides are ores of this metal. Pyrolusite is used as a colorant in the glass industry, because when oxidized to permanganate it takes on a violet coloration. The violet color is complementary to yellow and eliminates such coloration in glasses containing iron Fe +3 . It is also used to manufacture dry cells and to obtain chlorine.
  • The mercuric oxide(montroidita), given its rarity, is not used in its natural state, if not artificially obtained. It is used in medicine for the preparation of ointments for ophthalmological and dermatological use.

 

Leave a Comment