There are chemical elements, showing different degrees of oxidation, which allows to form in the course of chemical reactions a large number of compounds with defined properties. Knowing the electronic structure of the atom, it is possible to assume, what substances will be formed.
The degree of oxidation of nitrogen can vary from -3 to +5, which indicates the diversity of compounds based on it.
Nitrogen belongs to the chemical elements located in the 15th group, in the second period in the periodic table of Mendeleev D.I. He is assigned the sequence number 7 and the abbreviated letter designation N. Under normal conditions, a relatively inert element, special conditions are necessary for carrying out reactions.
In nature, it occurs in the form of a diatomic colorless gas of atmospheric air with a volume fraction of more than 75%. Contained in the composition of protein molecules, acids of nucleic and nitrogen-containing substances of inorganic origin.
To determine the degree of oxidation of nitrogen in compounds, it is necessary to know its nuclear structure and study the electron shells.
The natural element is represented by two stable isotopes, with a mass number of 14 or 15. The first nucleus contains 7 neutron and 7 proton particles, and the second contains 1 more neutron particle.
There are artificial varieties of its atom with a mass of 12-13 and 16-17, with unstable nuclei.
In the study of the electronic structure of atomic nitrogen is seen that there are two electron shells (inner and outer). On a 1s-orbital contains one pair of electrons.
On the second outer shell, there are only five negatively charged particles: two at the 2s sublevel and three at the 2p orbital. The valence energy level does not have free cells, which indicates the impossibility of separating its electron pair. The 2p orbital is considered only half filled with electrons, which makes it possible to attach 3 negatively charged particles. In this case, the degree of oxidation of nitrogen is -3.
Given the structure of the orbitals, it can be concluded that this element with the coordination number 4 is maximally associated with only four other atoms. For the formation of three bonds, an exchange mechanism is used, another one is formed by the donor-acceptor method.
Nitrogen oxidation in various compounds
The maximum number of negative particles, which is able to connect his atom, is equal to 3. In this case, it manifested a degree of oxidation equal to 3, the inherent compounds of the type NH3 or ammonia, NH4 + or ammonium and nitrides Me3 N2. The latter substances are formed with increasing temperature by reacting nitrogen with metal atoms.
The largest number of negatively charged particles that an element is able to give is equal to 5.
Two nitrogen atoms can bind to each other to form stable compounds with oxidation state -2. Such a relationship is observed in N2 H4 or hydrazines, in azides of various metals or MeN3. A nitrogen atom attaches 2 electrons to free orbitals.
There is a degree of oxidation of -1, when the element 1 receives only the negative particle. For example, in NH2 OH or hydroxylamine is negatively charged.
There are positive sign of the degree of oxidation of nitrogen, when the outer layer get the energy e of the particle. They vary from 1 to 5.
Charge 1+ is present in nitrogen in N2 O (monovalent oxide) and in sodium hyonitrite with the formula Na2 N2 O2 .
In NO (a bivalent oxide), the element gives up two electrons and is charged positively (+2).
There is a degree of oxidation of nitrogen 3 (in the compound NaNO2 or nitride and in trivalent oxide). In this case, 3 electrons are split off.
A charge of +4 occurs in an oxide with a valence IV or its dimer (N2 O4 ).
The positive sign of the oxidation state (+5) appears in N2 O5 or in pentavalent oxide, in nitric acid and its derivatives.
Compounds from nitrogen with hydrogen
Natural substances on the basis of two above elements reminiscent of organic hydrocarbons. Only isotonicity lose its stability with increasing atomic number of nitrogen.
The most significant hydrogen compounds include molecules of ammonia, hydrazine and hydrazoic acid. They are obtained by reacting hydrogen with nitrogen, and in the latter matter there is also oxygen.
What is ammonia
It is also called hydrogen nitride, and its chemical formula is denoted as NH3 with a mass of 17. In conditions with normal temperature and pressure, ammonia has the form of a colorless gas with a strong odor of ammonia. By density, it is 2 times less than air, easily dissolves in the aquatic environment due to the polar structure of its molecule. Treats low-hazard substances.
In industrial volumes, ammonia is obtained by catalytic synthesis from hydrogen and nitrogen molecules. There are laboratory methods for obtaining nitrite from ammonium salts and sodium.
Part of the pyramidal molecule has one nitrogen and 3 hydrogen atoms. They are located relative to each other at an angle of 107 degrees. In the molecule, having the shape of a tetrahedron, the nitrogen located at the center. Due to the three unpaired p-electrons it connects the polar covalent bonds of nature 3 atomic hydrogens, which have 1 s-electron. The so formed ammonia molecule. In this case, the nitrogen atom in oxidation state -3.
This item is still unshared pair of electrons on the outer level, which creates a covalent bond with a hydrogen ion with a positive charge. One element is the donor negatively charged particles, and the other the acceptor. This forms the ammonium ion NH4 + .
What is ammonium
It is referred to as positively charged polyatomic ions or cations. Ammonium is also considered a chemical substance that cannot exist in the form of a molecule. It consists of ammonia and hydrogen.
Ammonium with a positive charge in the presence of various anions with a negative sign is capable of forming ammonium salts, in which it behaves like metals with valence I. It is also with his participation that ammonium compounds are synthesized.
Many ammonium salts are in the form of a colorless crystalline substances which are readily soluble with water. If the connections of the ion NH4 + are formed by volatile acids, then under conditions of heating, they decompose and release gaseous substances. Their subsequent cooling leads to a reversible process.
The stability of such salts depends on the strength of the acids from which they are formed. Stable ammonium compounds correspond to a strong acid residue. For example, stable ammonium chloride is made from hydrochloric acid. At temperatures up to 25 degrees, this salt does not decompose, which cannot be said of ammonium carbonate. The latter compound is often used in cooking for raising dough, replacing baking soda.
Bakers ammonium carbonate referred to simply as ammonia. This salt is used by brewers to improve the fermentation of brewer's yeast.
Qualitative reaction for the detection of ammonium ions is the action of alkali metal hydroxides on its connections. In the presence of NH4 + ammonia is released.
Ammonium chemical structure
The configuration of its ion resembles a regular tetrahedron with nitrogen in its center. Hydrogen atoms are located on the tops of the figure. To calculate the degree of oxidation of nitrogen in ammonium, it must be remembered that the total charge of the cation is +1, and each hydrogen ion has one electron, and there are only 4. The total hydrogen potential is +4. If we subtract the charge of all hydrogen ions from the charge of the cation, we get: +1 - (+4) = -3. This means that nitrogen has an oxidation state of -3. In this case, it attaches three electrons.
What are nitrides
Nitrogen is able to combine with more electropositive atoms of a metallic and nonmetallic nature. As a result, compounds similar to hydrides and carbides are formed. Such nitrogen-containing substances are called nitrides. Between the metal and the nitrogen atom in the compounds emit covalent, ionic and intermediate bonds. It is this characteristic that underlies their classification.
Covalent nitrides include compounds in the chemical bond of which electrons do not pass from atomic nitrogen, but form together with negatively charged particles of other atoms a common electron cloud.
Examples of such substances are hydrogen nitrides, such as ammonia and hydrazine molecules, as well as nitrogen halides, which include trichlorides, tribromides and trifluorides. They share a common electron pair equally belongs to two atoms.
The ionic nitrides include compounds with a chemical bond formed by the transfer of electrons from the metal element on the free levels of nitrogen. In molecules of such substances observed polarity. The nitrides have the oxidation state of nitrogen is 3-. Accordingly, the total charge of the metal is 3 .
Such compounds include nitrides of magnesium, lithium, zinc or copper, with the exception of alkali metals. They have a high melting point.
The nitrides with an intermediate connection are substances which have the evenly distributed metal atoms and nitrogen and there is no clear displacement of the electron cloud. Such inert compounds belong to the nitrides of iron, molybdenum, manganese and tungsten .
Description of ferric oxide
It is also called anhydride, obtained from nitrous acid, having the formula HNO2. Considering the oxidation of nitrogen (3 ) oxygen (2-) trioxide, it turns out the ratio of atoms of elements 2 3 or N2 O3 .
The liquid and gaseous forms of the anhydride are highly unstable compounds, they easily decompose into 2 different oxides with valences IV and II.