Nitrogen oxidation state. Nitrogen oxidation state - learning to understand Nitrogen oxidation state 4 in the compound

Nitrogen is perhaps the most common chemical element in the entire solar system. To be more specific, nitrogen is the 4th most abundant. Nitrogen in nature is an inert gas.

This gas is colorless and odorless and very difficult to dissolve in water. However, nitrate salts tend to react very well with water. Nitrogen has a low density.

Nitrogen is an amazing element. There is an assumption that it got its name from the ancient Greek language, which means “lifeless, spoiled” in translation from it. Why such a negative attitude towards nitrogen? After all, we know that it is part of proteins, and breathing without it is almost impossible. Nitrogen plays an important role in nature. But in the atmosphere this gas is inert. If it is taken as it is in its original form, then many side effects are possible. The victim may even die from suffocation. After all, nitrogen is called lifeless because it does not support combustion or respiration.

Under normal conditions, such a gas reacts only with lithium, forming a compound such as lithium nitride Li3N. As we can see, the oxidation state of nitrogen in such a compound is -3. With other metals, and of course, it also reacts, but only when heated or when using various catalysts. By the way, -3 is the lowest oxidation state of nitrogen, since only 3 electrons are needed to completely fill the outer energy level.

This indicator has various meanings. Each oxidation state of nitrogen has its own compound. It is better to just remember such connections.

5 - the highest degree of oxidation of nitrogen. Occurs in and in all nitrate salts.

Task number 1

The +2 oxidation state in all compounds exhibits

Answer: 4

Explanation:

Of all the proposed options, the +2 oxidation state in complex compounds is shown only by zinc, being an element of the secondary subgroup of the second group, where the maximum oxidation state is equal to the group number.

Tin - an element of the main subgroup of group IV, a metal, exhibits oxidation states 0 (in a simple substance), +2, +4 (group number).

Phosphorus is an element of the main subgroup of the main group, being a non-metal, it exhibits oxidation states from -3 (group number - 8) to +5 (group number).

Iron is a metal, the element is located in a secondary subgroup of the main group. For iron, oxidation states are characteristic: 0, +2, +3, +6.

Task number 2

The compound of the composition KEO 4 forms each of the two elements:

1) phosphorus and chlorine

2) fluorine and manganese

3) chlorine and manganese

4) silicon and bromine

Answer: 3

Explanation:

The salt of the KEO 4 composition contains the acid residue EO 4 - , where oxygen has an oxidation state of -2, therefore, the oxidation state of the element E in this acid residue is +7. Of the proposed options, chlorine and manganese are suitable - elements of the main and secondary subgroups of group VII, respectively.

Fluorine is also an element of the main subgroup of group VII, however, being the most electronegative element, it does not show positive oxidation states (0 and -1).

Boron, silicon and phosphorus are elements of the main subgroups of groups 3, 4 and 5, respectively, therefore, in salts, they exhibit the corresponding maximum oxidation states of +3, +4, +5.

Task number 3

1. Zn and Cr
2. Si and B
3. Fe and Mn
4.P and As

Answer: 4

Explanation:

The same highest oxidation state in the compounds, equal to the group number (+5), is shown by P and As. These elements are located in the main subgroup of group V.

Zn and Cr are elements of secondary subgroups of groups II and VI, respectively. In compounds, zinc exhibits the highest oxidation state +2, chromium - +6.

Fe and Mn are elements of the secondary subgroups of groups VIII and VII, respectively. The highest oxidation state for iron is +6, for manganese - +7.

Task number 4

The same highest oxidation state in compounds exhibit

1. Hg and Cr
2. Si and Al
3.F and Mn
4. P and N

Answer: 4

Explanation:

P and N show the same highest oxidation state in compounds, equal to the group number (+5). These elements are located in the main subgroup of group V.

Hg and Cr are elements of secondary subgroups of groups II and VI, respectively. In compounds, mercury exhibits the highest oxidation state +2, chromium - +6.

Si and Al are elements of the main subgroups of groups IV and III, respectively. Therefore, for silicon, the maximum oxidation state in complex compounds is +4 (the group number where silicon is located), for aluminum - +3 (the group number where aluminum is located).

F and Mn are elements of the main and secondary subgroups of groups VII, respectively. However, fluorine, being the most electronegative element of the Periodic Table of Chemical Elements, does not show positive oxidation states: in complex compounds, its oxidation state is -1 (group number -8). The highest oxidation state of manganese is +7.

Task number 5

The +3 oxidation state nitrogen exhibits in each of two substances:

1. HNO 2 and NH 3
2. NH 4 Cl and N 2 O 3
3. NaNO 2 and NF 3
4. HNO 3 and N 2

Answer: 3

Explanation:

In nitrous acid HNO 2, the oxidation state of oxygen in the acid residue is -2, for hydrogen - +1, therefore, in order for the molecule to remain electrically neutral, the oxidation state of nitrogen is +3. In ammonia, NH 3, nitrogen is a more electronegative element, therefore it pulls the electron pair of a covalent polar bond onto itself and has a negative oxidation state of -3, the oxidation state of hydrogen in ammonia is +1.

Ammonium chloride NH 4 Cl is an ammonium salt, so the oxidation state of nitrogen is the same as in ammonia, i.e. equals -3. In oxides, the oxidation state of oxygen is always -2, so for nitrogen it is +3.

In sodium nitrite NaNO 2 (salts of nitrous acid), the degree of oxidation of nitrogen is the same as in nitrogen in nitrous acid, because is +3. In nitrogen fluoride, the oxidation state of nitrogen is +3, since fluorine is the most electronegative element in the Periodic Table and in complex compounds it exhibits a negative oxidation state of -1. This answer option satisfies the condition of the task.

In nitric acid, nitrogen has the highest oxidation state, equal to the group number (+5). Nitrogen as a simple compound (since it consists of atoms of one chemical element) has an oxidation state of 0.

Task number 6

The highest oxide of an element of group VI corresponds to the formula

1. E 4 O 6
2.EO 4
3. EO 2
4. EO 3

Answer: 4

Explanation:

The highest oxide of an element is the oxide of the element with its highest oxidation state. In a group, the highest oxidation state of an element is equal to the group number, therefore, in group VI, the maximum oxidation state of an element is +6. In oxides, oxygen exhibits an oxidation state of -2. The numbers below the element symbol are called indices and indicate the number of atoms of this element in the molecule.

The first option is incorrect, because the element has an oxidation state of 0-(-2)⋅6/4 = +3.

In the second version, the element has an oxidation state of 0-(-2) ⋅ 4 = +8.

In the third variant, the oxidation state of the element E: 0-(-2) ⋅ 2 = +4.

In the fourth variant, the oxidation state of the element E: 0-(-2) ⋅ 3 = +6, i.e. this is the desired answer.

Task number 7

The oxidation state of chromium in ammonium dichromate (NH 4) 2 Cr 2 O 7 is

1. +6
2. +2
3. +3
4. +7

Answer: 1

Explanation:

In ammonium dichromate (NH 4) 2 Cr 2 O 7 in the ammonium cation NH 4 + nitrogen, as a more electronegative element, has a lower oxidation state of -3, hydrogen is positively charged +1. Therefore, the entire cation has a charge of +1, but since there are 2 of these cations, the total charge is +2.

In order for the molecule to remain electrically neutral, the acid residue Cr 2 O 7 2− must have a charge of -2. Oxygen in the acid residues of acids and salts always has a charge of -2, therefore, 7 oxygen atoms that make up the ammonium bichromate molecule are charged -14. Chromium atoms Cr into molecules 2, therefore, if the charge of chromium is denoted by x, then we have:

2x + 7 ⋅ (-2) = -2 where x = +6. The charge of chromium in the ammonium dichromate molecule is +6.

Task number 8

An oxidation state of +5 is possible for each of the two elements:

1) oxygen and phosphorus

2) carbon and bromine

3) chlorine and phosphorus

4) sulfur and silicon

Answer: 3

Explanation:

In the first proposed answer, only phosphorus, as an element of the main subgroup of group V, can exhibit an oxidation state of +5, which is the maximum for it. Oxygen (an element of the main subgroup of group VI), being an element with high electronegativity, in oxides exhibits an oxidation state of -2, as a simple substance - 0, and in combination with fluorine OF 2 - +1. The +5 oxidation state is not typical for it.

Carbon and bromine are elements of the main subgroups of groups IV and VII, respectively. Carbon is characterized by a maximum oxidation state of +4 (equal to the group number), and bromine exhibits oxidation states of -1, 0 (in a simple compound Br 2), +1, +3, +5 and +7.

Chlorine and phosphorus are elements of the main subgroups of groups VII and V, respectively. Phosphorus exhibits a maximum oxidation state of +5 (equal to the group number), for chlorine, similarly to bromine, oxidation states of -1, 0 (in a simple compound Cl 2), +1, +3, +5, +7 are characteristic.

Sulfur and silicon are elements of the main subgroups of groups VI and IV, respectively. Sulfur exhibits a wide range of oxidation states from -2 (group number - 8) to +6 (group number). For silicon, the maximum oxidation state is +4 (group number).

Task number 9

1. NaNO3
2. NaNO2
3.NH4Cl
4. NO

Answer: 1

Explanation:

In sodium nitrate NaNO 3, sodium has an oxidation state of +1 (group I element), there are 3 oxygen atoms in the acid residue, each of which has an oxidation state of −2, therefore, in order for the molecule to remain electrically neutral, nitrogen must have an oxidation state of: 0 − (+ 1) − (−2) 3 = +5.

In sodium nitrite NaNO 2, the sodium atom also has an oxidation state of +1 (group I element), there are 2 oxygen atoms in the acid residue, each of which has an oxidation state of −2, therefore, in order for the molecule to remain electrically neutral, nitrogen must have an oxidation state: 0 − (+1) − (−2) 2 = +3.

NH 4 Cl - ammonium chloride. In chlorides, chlorine atoms have an oxidation state of −1, hydrogen atoms, of which there are 4 in the molecule, are positively charged, therefore, in order for the molecule to remain electrically neutral, the nitrogen oxidation state is: 0 − (−1) − 4 (+1) = −3. In ammonia and cations of ammonium salts, nitrogen has a minimum oxidation state of −3 (the number of the group in which the element is located is −8).

In the nitric oxide NO molecule, oxygen exhibits a minimum oxidation state of −2, as in all oxides, therefore, the oxidation state of nitrogen is +2.

Task number 10

Nitrogen exhibits the highest oxidation state in a compound whose formula is

1. Fe(NO 3) 3
2. NaNO2
3. (NH 4) 2 SO 4
4 NO 2

Answer: 1

Explanation:

Nitrogen is an element of the main subgroup of group V, therefore, it can exhibit a maximum oxidation state equal to the group number, i.e. +5.

One structural unit of iron nitrate Fe(NO 3) 3 consists of one Fe 3+ ion and three nitrate ions. In nitrate ions, nitrogen atoms, regardless of the type of counterion, have an oxidation state of +5.

In sodium nitrite NaNO 2, sodium has an oxidation state of +1 (an element of the main subgroup of group I), there are 2 oxygen atoms in the acid residue, each of which has an oxidation state of −2, therefore, in order for the molecule to remain electrically neutral, nitrogen must have an oxidation state of 0 − ( +1) − (−2)⋅2 = +3.

(NH 4) 2 SO 4 - ammonium sulfate. In sulfuric acid salts, the SO 4 2− anion has a charge of 2−, therefore, each ammonium cation is charged with 1+. On hydrogen, the charge is +1, therefore on nitrogen -3 (nitrogen is more electronegative, therefore it pulls the common electron pair of the N−H bond). In ammonia and cations of ammonium salts, nitrogen has a minimum oxidation state of −3 (the number of the group in which the element is located is −8).

In the nitric oxide NO 2 molecule, oxygen exhibits a minimum oxidation state of −2, as in all oxides, therefore, the oxidation state of nitrogen is +4.

Task number 11

28910E

In compounds of the composition Fe(NO 3) 3 and CF 4, the degree of oxidation of nitrogen and carbon is, respectively,

Answer: 4

Explanation:

One structural unit of iron (III) nitrate Fe(NO 3) 3 consists of one iron ion Fe 3+ and three nitrate ions NO 3 − . In nitrate ions, nitrogen always has an oxidation state of +5.

In carbon fluoride CF 4, fluorine is a more electronegative element and pulls the common electron pair of the C-F bond towards itself, showing an oxidation state of -1. Therefore, carbon C has an oxidation state of +4.

Task number 12

A32B0B

The oxidation state +7 chlorine exhibits in each of the two compounds:

1. Ca(OCl) 2 and Cl 2 O 7
2. KClO 3 and ClO 2
3. BaCl 2 and HClO 4
4. Mg(ClO 4) 2 and Cl 2 O 7

Answer: 4

Explanation:

In the first variant, chlorine atoms have oxidation states +1 and +7, respectively. One structural unit of calcium hypochlorite Ca(OCl) 2 consists of one calcium ion Ca 2+ (Ca is an element of the main subgroup of group II) and two hypochlorite ions OCl − , each of which has a charge of 1−. In complex compounds, except for OF 2 and various peroxides, oxygen always has an oxidation state of −2, so it is obvious that chlorine has a charge of +1. In chlorine oxide Cl 2 O 7, as in all oxides, oxygen has an oxidation state of −2, therefore, chlorine in this compound has an oxidation state of +7.

In potassium chlorate KClO 3, the potassium atom has an oxidation state of +1, and oxygen - -2. In order for the molecule to remain electrically neutral, chlorine must exhibit an oxidation state of +5. In chlorine oxide ClO 2, oxygen, as in any other oxide, has an oxidation state of −2, therefore, for chlorine, its oxidation state is +4.

In the third version, the barium cation in the complex compound is charged +2, therefore, a negative charge of −1 is concentrated on each chlorine anion in the BaCl 2 salt. In perchloric acid HClO 4, the total charge of 4 oxygen atoms is -2⋅4 = -8, on the hydrogen cation the charge is +1. For the molecule to remain electrically neutral, the charge of chlorine must be +7.

In the fourth variant, in the magnesium perchlorate molecule Mg (ClO 4) 2, the charge of magnesium is +2 (in all complex compounds, magnesium exhibits an oxidation state of +2), therefore, each ClO 4 - anion has a charge of 1 -. In total, 4 oxygen ions, where each exhibits an oxidation state of -2, have a charge of -8. Therefore, for the total charge of the anion to be 1−, the charge on chlorine must be +7. In chlorine oxide Cl 2 O 7 , as explained above, the charge of chlorine is +7.

DEFINITION

Nitrogen is the seventh element in the Periodic Table. It is located in the second period of the V group of the A subgroup. Designation - N.

Nitrogen is a typical non-metallic element, in terms of electronegativity (3.0) it is second only to fluorine and oxygen.

Natural nitrogen consists of two stable isotopes 14 N (99.635%) and 15 N (0.365%).

The nitrogen molecule is diatomic. There is a triple bond between the nitrogen atoms in the molecule, as a result of which the N 2 molecule is exceptionally strong. Molecular nitrogen is chemically inactive, weakly polarized.

Under normal conditions, molecular nitrogen is a gas. The melting points (-210 o C) and boiling points (-195.8 o C) of nitrogen are very low; it is poorly soluble in water and other solvents.

The oxidation state of nitrogen in compounds

Nitrogen forms diatomic molecules of the composition N 2 due to the induction of covalent non-polar bonds, and, as is known, in compounds with non-polar bonds, the oxidation state of the elements is zero.

Nitrogen is characterized by a whole range of oxidation states, among which there are both positive and negative.

Oxidation state (-3) nitrogen manifests itself in compounds called nitrides (Mg +2 3 N -3 2, B +3 N -3), the most famous of which is ammonia (N -3 H +1 3).

Oxidation state (-2) nitrogen manifests itself in peroxide-type compounds - pernitrides, the simplest representative of which is hydrazine (diamide / hydrogen pernitride) - N -2 2 H 2.

In a compound called hydroxylamine - N -1 H 2 OH-nitrogen shows the oxidation state (-1) .

The most stable positive nitrogen oxidation states are (+3) And (+5) . He exhibits the first of them in fluoride (N +3 F -1 3), oxide (N +3 2 O -2 3), oxohalides (N +3 OCl, N +3 OBr, etc.), as well as derivatives anion NO 2 - (KN + 3 O 2, NaN + 3 O 2, etc.). The oxidation state (+5) nitrogen shows in oxide N + 5 2 O 5, oxonitride N + 5 ON, dioxofluoride N + 5 O 2 F, as well as in trioxonitrate (V) -ion NO 3 - and dinitridonitrate (V) -ion NH 2 -.

Nitrogen also exhibits oxidation states (+1) - N +1 2 O, (+2) - N +2 O and (+4) N +4 O 2 in their compounds, but much less frequently.

Examples of problem solving

EXAMPLE 1

The task

Indicate the oxidation states of oxygen in the compounds: La 2 O 3 , Cl 2 O 7 , H 2 O 2 , Na 2 O 2 , BaO 2 , KO 2 , KO 3 , O 2 , OF 2 .

Answer

Oxygen forms several types of binary compounds in which it exhibits characteristic oxidation states. So, if oxygen is part of oxides, then its oxidation state is (-2), as in La 2 O 3 and Cl 2 O 7.

In peroxides, the oxidation state of oxygen is (-1): H 2 O 2 , Na 2 O 2 , BaO 2 .

In combination with fluorine (OF 2), the oxidation state of oxygen is (+2).

The oxidation state of an element in a simple substance is always zero (O o 2).

Substances of the composition KO 2 and KO 3 are superperoxide (superoxide) and potassium ozonide, in which oxygen exhibits fractional values of oxidation states: (-1/2) and (-1/3).

Answer

(-2), (-2), (-1), (-1), (-1), (-1/2), (-1/3), 0 and (+2).

EXAMPLE 2

The task	Indicate the oxidation states of nitrogen in the compounds: NH 3 , N 2 H 4 , NH 2 OH, N 2 , N 2 O, NO, N 2 O 3 , NO 2 , N 2 O 5 .
Solution	The oxidation state of an element in a simple substance is always zero (N o 2). It is known that in oxides the oxidation state of oxygen is (-2). Using the electroneutrality equation, we determine that the oxidation states of nitrogen in oxides are: N +1 2 O, N +2 O, N +3 2 O 3, N +4 O 2, N +5 2 O 5.