Dual compound


means a binary compound of mainly inorganic compound molecule is composed of two elements of a compound, or a compound of formula contains only two elements. Such as sodium chloride NaCl, silver bromide, AgBr, water, H₂O and the like. Named binary compounds, is in the middle of two elements linked with the name "" of the word, before the element name in a negative valence, n is the valence of the element name on.

diet named

Generally speaking, a binary compound named two forms follows:

"of a certain" - if the price of a compound of elements state are its most common valence state, and the name does not lead to ambiguity. It is customary in a negative valence of the elements on the front when naming. Such as: sodium chloride, potassium sulfide -K2S -NaCl divalent, when the element becomes more compounds or elements as a main valence than the valence of the above named cause ambiguity. Then we can solve the three methods: "a few one of a few." Such as: dioxygen difluoride -O2F2 four -S4N4 number "of a certain ()", the Roman numerals in parentheses is written nitride oxide tetrasulfide. Commonly used in naming a strong ionic compound. Such as: titanium (IV) chloride -TiCl4 titanium (III) chloride -TiCl3 "of a High / one alkylene", used in the relatively fixed element having a variable valence. In this common method named elements comprising: Fe- iron; ferrous Fe- Cu Cu-; Cu- Co- cuprous cobalt; Co- mercury Hg-cobalt; mercurous Hg-Tl- thallium / thallium high; Tl - Sn- thallium, tin / tin high; Sn- stannous Mn- permanganate; Mn- manganese.

Transitional metals

"Latin expressions" Metal Latin name + "-ic" (for high) / "-ous" (with to Low) + nonmetallic + "-ide" For example: ferrous chloride -Ferrous chloride, cuprous chloride -Cuprous chloride dibasic acid (aq) "Hydro-" + nonmetallic + "-ic" + "acid "only about 10 nonmetal may be formed two yuan acid (divalent herein does not refer to the number of hydrogen atoms can be ionized, and refers to the number of elements in an acid) and hydrogen: chlorine, fluorine, bromine, iodine and sulfur. They show named using the following formula: For example: -Hydrochloric hydrochloric acid, hydrofluoric acid -Hydrofluoric acid

two yuan covalent compounds

nonmetallic + nonmetallic + "-ide" before an element is combined with the appropriate amount of the compound expressed Latin prefix one element atoms in the molecule. This method is usually not used in an ion compound (see below). For example, K2O generally do not call Dipotassium monoxide, simply called Potassium oxide. The P4O6, but said tetraphosphorus hexoxide. Some elements of names beginning with a vowel (such as oxygen Oxygen), you need to cancel the prefix letter and use the first letter of the last name of the elements, such as: mono- + Oxide = Monoxide, O4 = Tetroxide, O5 = Pentoxide, and so on.

If the first element is a single atom can not add "mono-".


Mono -


Tri -


Penta -


< / td>

Hepta -


Nona -


Di -


Tetra -


Hexa -


Octa -


Deca -

For example: phosphorus pentafluoride -Phosphorus pentafluoride, heptafluoropropyl iodide -Iodine heptafluoride

binary ionic compounds

monatomic anionic: cationic + anionic + "ide" For example: magnesium sulfate -Magnesium sulfide

thermal stability of binary compounds

If a compound when heated, due to the intensification of the outer electron vibration, resulting electron cloud strongly biased to the positive ion one, if the deformation is large enough negative ion, or the anion of a few electronically over the positive ions into the housing of the electronic repulsion of positive ions of atomic orbitals and for it all, so it is accompanied by decomposition of the compound. The thermal decomposition reaction of the copper halide is

2CuX2 = 2CuX + X2

each polarization larger, the lower the decomposition temperature, see the following data:



CuCl2 CuBr2 CuI2
decomposition temperature / ° C 950 500 490 absent


oxygen binary compounds of elements with other elements are formed. Such as calcium oxide, sulfur dioxide, nitric oxide and the like. Oxide can be divided into non-salt oxides (such as carbon monoxide, nitric oxide, etc.) and a salt oxides types, the latter is divided into basic oxides (such as calcium oxide), amphoteric oxide (such as alumina) and acidic oxides (such as carbon dioxide). There are also peroxide, superoxide, smelly oxides. The same elements often have several different valence oxides, such as SO 2 and SO3, FeO, Fe 2 O 3 and Fe < sub> 3O 4 and the like. Sometimes oxide broader meaning, is not limited to binary compounds containing oxygen, such as an oxide polyols (e.g., NiFe 2 O 4 ) and organic oxides (such as ethylene C 2 H 4 O, i.e., ethylene oxide) and the like.

Dual compound

In addition to helium, neon, krypton, have encountered all elements form an oxide, and easily exhibits the highest oxidation state of the element. Press valence ionic characteristics can be divided oxides (e.g., sodium oxide) and covalent oxides (such as carbon dioxide, beryllium oxide); structure can be divided according to different oxides, peroxides, superoxides, ozonides, etc. ; its pH in aqueous solution can be divided into basic oxides (such as calcium oxide), acid oxides (e.g. sulfur trioxide), amphoteric oxide (e.g., zinc oxide, aluminum), and the neutral oxide , also known as inert oxides (such as carbon monoxide, nitric oxide), which is insoluble in acid, is insoluble in dilute alkali; In addition, according to the composition can be divided into metal oxides (e.g., sodium oxide), non-metal oxides (e.g. nitrogen dioxide), mixed oxides (e.g., triiron tetroxide), and non-stoichiometric oxides (e.g., FeO 0.90 , FeO 0.95 ) and the like. Recent studies show mixed oxide, triiron tetraoxide, lead oxide is actually Fe (Ⅲ) ferric FeFe [FeO 4 ] and lead (Ⅳ) Lead (Ⅱ) Pb 2 [PbO 4 ], a salt, it was also known dummy oxide. Non-stoichiometric oxides are usually arranged in a close packed by O, fill some of the gaps formed by the metal ions. When one element may be formed of several oxides, generally highest oxidation state acidity, basicity low oxidation state, such as chromium oxide of CrO (basic), chromium oxide Cr 2 O 3 (females) and chromium trioxide CrO 3 (acidic). Peroxide containing O 2 , can be seen as a salt of hydrogen peroxide, highly electropositive alkali metal, calcium, strontium, barium can form ionic peroxide, sodium peroxide absorption of carbon dioxide in the air discharge oxygen. Superoxide containing superoxide anion O 2 , potassium, rubidium, cesium, calcium, strontium, barium Jieke formed MO 2 or MO 4 super oxides, their hygroscopic, are put oxygen, water and dilute acids also releases oxygen when heated. Ozone containing ozonide ion O 3 , alkali metal, alkaline earth metal, an ammonium ion Jieneng formed ozonide, are typical salts, easily decomposed, such as potassium superoxide smelly decomposition of potassium and oxygen, oxidation resistant. It has very important applications in various types of oxide actually. Wherein all the short period element oxides are colorless, long period of many elements in the oxide is colored, some even more lower oxidation state oxides colored. Highest beryllium, magnesium, calcium, zirconium, hafnium, thorium oxide melting point between 2 500 ~ 3000 ℃, multi refractory material used.


means a binary compound of carbon and smaller than its electronegativity, or similar element with its bonded, not including the carbon and oxygen, sulfur, phosphorus, nitrogen and a halogen compound is formed. According to the characteristics of the bonding, the carbide may be divided into three types: ionic, covalent, between the filling.

① ionic salt carbides, also known as type carbides. Mainly ⅠA, ⅡA, ⅢA, ⅠB, binary compounds ⅡB elements (except the outer Hg) and some transition elements f (f electrons is not filled) with carbon formation. Some containing C and C 2 . C-containing carbides, methane released during hydrolysis, may be referred to methanation, for example beryllium carbide Be 2 C carbide and aluminum Al 4 C 3 latter hydrolyzing the formula:

Al 4 C 3 + 12H 2 O = 4Al (OH) < sub> 3+ 3CH 4

containing C 2 compounds, acetylene released upon hydrolysis, also known acetylide. For example:

CaC 2 + 2H 2 O = HCCH + Ca (OH) 2

② filling between metal carbides, also known as type carbide. Mainly d-transition elements, in particular VIB, Group ⅦB binary compounds of elements with iron and carbon formation. Structure is characterized by the carbon atoms occupy the octahedral cavities arranged in close-packed metal atoms. Property is a very high melting point (3000 ~ 4800 ℃), hardness (Mohs hardness 7 to 10) and having a conductive metal. Is greater than the atomic radius of the metal, the carbon atom 130pm embedded metal lattice strain not only the lattice further solid, thus increasing the hardness and improving the melting point. The atomic radius of less than 130pm metals, such as chromium, manganese, iron, cobalt and nickel, the metal lattice distortion is apparent, the nature of the metal carbide is between ionic and mesenchymal type, rather easily in water and dilute acid hydrolysis hydrocarbons and hydrogen.

③ covalent carbide is mainly silicon and boron carbide. Carbon atoms to silicon, electronegativity proximity boron atom, can be obtained entirely covalent compound, which has high hardness, high melting point and chemical stability characteristics.

ionic calcium carbide carbide is an important raw material of acetylene and other chemical agents. Mesenchymal carbides of high hardness, good electrical conductivity, such as tungsten carbide and tantalum carbide alloy is an important component of the ceramic composite material. Covalent boron carbide and silicon carbide have been used as an abrasive. Typically through a carbon or metal oxide and metal response from the system at a high temperature carbide 1000 ~ 2800 ℃; in some cases, be prepared by the hydrocarbon or hydrogen reduction of metal oxides or chlorides.

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