How to make an electronic formula for chemistry. Chemical formulas

Algorithm for the preparation of electronic formula of the element:

1. Determine the number of electrons in the atom using the periodic table of the chemical elements of D.I. Mendeleeva.

2. By the period of the period in which the element is located, determine the number of energy levels; The number of electrons in the last electronic level corresponds to the number number.

3. Located levels on the supro and orbitals and fill them with electrons in accordance with the rules of filling orbitals:

It must be remembered that at the first level there is a maximum of 2 electrons 1s 2., on the second - maximum 8 (two s.and six r: 2S 2 2p 6), on the third - maximum 18 (two s., six p., and ten d: 3S 2 3P 6 3D 10).

The main quantum number n. Must be minimal.
The first is filled s-subline, then r-, D- B F-sill.
Electrons fill orbital in order of increasing orbital energy (Clakovsky rule).
Within the subproduction, the electrons first occupy free orbitals, and only after that form pairs (Hinda rule).
On one orbital there can be no more than two electrons (Pauli principle).

Examples.

1. Make an electronic formula for nitrogen. In the periodic table of nitrogen is under No. 7.

2. Make an electronic formula for Argon. In the periodic table, Argon is under No. 18.

1S 2 2S 2 2P 6 3S 2 3P 6.

3. Make an electronic chromium formula. In the periodic table chrome is under No. 24.

1s. 2 2s. 2 2p. 6 3s. 2 3P. 6 4S. 1 3D 5

Energy diagram zinc.

4. Make an electronic zinc formula. In the periodic table zinc is under No. 30.

1S 2 2S 2 2P 6 3S 2 3P 6 4S 2 3D 10

We note that part of the electronic formula, namely 1S 2 2S 2 2p 6 3S 2 3p 6 is an electronic argon formula.

The electronic zinc formula can be represented as.

The location of electrons on energy shells or levels is recorded using electronic formulas of chemical elements. Electronic formulas or configurations help to represent the structure of an element atom.

Building atom

Atoms of all elements consist of a positively charged kernel and negatively charged electrons that are located around the kernel.

Electrons are located at different energy levels. The further electron is from the kernel, the greater energy it has. The size of the energy level is determined by the size of the atomic orbital or the orbital cloud. This space in which the electron is moving.

Fig. 1. The overall structure of the atom.

Orbital may have a different geometric configuration:

s-orbitals - spherical;
r-, D and F-orbitals - Dumbbell, lying in different planes.

At the first energy level of any atom, there is always a S-orbital with two electrons (exception - hydrogen). Starting from the second level, at one level there are S- and P-orbitals.

Fig. 2. S-, R-, D and F-orbitals.

Orbital exist, regardless of their electrons on them and can be filled or vacant.

Record formula

Electronic configurations of atoms of chemical elements are recorded in the following principles:

each energy level corresponds to the sequence number indicated by the Arabic digit;
the number follows the letter, meaning an orbital;
above the letter is written the upper index corresponding to the number of electrons into orbitals.

Examples of recording:

calcium -
1S 2 2S 2 2P 6 3S 2 3P 6 4S 2;
oxygen -
1s 2 2S 2 2P 4;
carbon -
1s 2 2S 2 2p 2.

Record the electronic formula helps the Mendeleev table. The number of energy levels corresponds to the period number. On the charge of the atom and the number of electrons indicates the sequence number of the element. The group number shows how many valence electrons is at the external level.

For example, take Na. Sodium is in the first group, in the third period, under the 11 number. This means that the sodium atom has a positively charged kernel (contains 11 protons), around which 11 electrons are located on three energy levels. At the external level is one electron.

Recall that the first energy level contains an S-orbital with two electrons, and the second - s- and p-orbitals. It remains to fill the levels and get full record:

11 Na) 2) 8) 1 or 1S 2 2S 2 2P 6 3S 1.

For convenience, special tables of electronic formulas element are created. In the long periodic table of formulas are also indicated in each cell of the element.

Fig. 3. Table of electronic formulas.

For brevity in square brackets, elements are recorded, the electronic formula of which coincides with the beginning of the formula of the element. For example, an electronic magnesium formula - 3s 2, neon - 1s 2 2S 2 2p 6. Therefore, the complete magnesium formula is 1S 2 2S 2 2P 6 3S 2.

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Instruction

Electrons in the atom occupy free orbital sequences called the scale: 1S / 2S, 2P / 3S, 3P / 4S, 3D, 4P / 5S, 4D, 5P / 6S, 4D, 5D, 6P / 7S, 5F, 6D, 7P. Two electrons with opposite spins can be located on orbitals - rotation directions.

The structure of electronic shells is expressed using graphic electronic formulas. Use the matrix to write formulas. In one cell, one or two electrons with opposite spins can be located. Electrons are depicted by arrows. The matrix clearly shows that two electrons can be located on S-orbitals, on the P-orbital - 6, on D - 10, on F -14.

Record the sequence number and the element icon next to the matrix. In accordance with the energy scale, turn 1S, 2S, 2P, 3S, 3P, 4S levels, on two electrons into the cell. It turns out 2 + 2 + 6 + 2 + 6 + 2 \u003d 20 electrons. These levels are completely filled.

You have left five more electrons and an empty 3D level. Position electrons in D-supel cells starting on the left. Electrons with the same spins position in cells first one by one. If all the cells are filled, starting on the left, add according to the second electron with the opposite spin. Manganese has five D-electrons located one by one in each cell.

Electron graphic formulas clearly show the number of unpaired electrons that determine valence.

note

Remember that chemistry is an exception science. Atoms of side subgroups of the periodic system meets the "Squad" of the electron. For example, at chromium with a sequence number 24 one of the electrons from the 4S level goes into the D-level cell. There is a similar effect in molybdenum, niobium, etc. In addition, there is a notion of an excited state of an atom when paired electrons are sprinkled and go to neighboring orbitals. Therefore, in the preparation of electron-graphic formulas of elements of the fifth and subsequent periods of a side subgroup, follow with the reference book.

Sources:

how to make an electronic formula of the chemical element

Electrons are part of atoms. And complex substances, in turn, consist of these atoms (atoms form elements) and the electrons are divided by each other. The degree of oxidation shows which atom how many electronic electrons took to themselves, and how much he gave. This indicator can be.

You will need

Chemistry school textbook 8-9 Class of any author, Mendeleev Table, Electricity Table of Elements (printed in school textbooks in chemistry).

Instruction

To begin with, it is necessary to designate that the degree is a concept that accepts links for, that is, not deepening into the structure. If the element is in a free state, then this is the easiest case - a simple substance is formed, which means the degree of oxidation is zero. For example, hydrogen, oxygen, nitrogen, fluorine, etc.

In the complex substances, everything is different: the electrons between the atoms are unevenly distributed, and it is precisely the degree of oxidation that helps determine the number of removable or received electrons. The degree of oxidation can be positive and negative. At the plus electrons are given, in minus it is accepted. Some elements are preserved their degree of oxidation in various compounds, but many do not differ in this feature. It is necessary to remember the important rule - the sum of the oxidation degree is always equal to zero. The simplest example, gas from: knowing that the degree of oxygen oxidation in most cases is -2 and using the above-mentioned rule, it is possible to calculate the degree of oxidation for C. in the amount of C -2 zero gives only +2, which means the degree of carbon oxidation +2. Complete the task and take for calculations of gas CO2: the degree of oxygen oxidation is still -2, but its molecules in this case are two. Consequently, (-2) * 2 \u003d (-4). The number in the amount of C -4 giving zero, +4, that is, this gas has an oxidation degree of +4. An example is more complicated: H2SO4 - hydrogen the degree of oxidation is +1, at oxygen -2. In the combination of 2 hydrogen molecules and 4 oxygen, i.e. Charges will be, respectively, +2 and -8. In order to get zero in the amount, you need to add 6 pluses. So, the degree of oxidation of sulfur +6.

When it is difficult to determine in the compound, where plus, where minus, the electric negatant table is needed (it is easy to find it in the textbook on general chemistry). Metals often have a positive degree of oxidation, and non-metals are negative. But for example, PI3 is both non-metal elements. The table states that the electronenence of iodine is 2.6, and phosphorus 2.2. When compared, it turns out that 2.6 more than 2.2, that is, electrons are tightened towards iodine (iodine has a negative degree of oxidation). Following the above uncomplicated examples, you can easily determine the degree of oxidation of any element in the connections.

note

No need to confuse metals and non-metals, then the degree of oxidation will be easier to find and not get confused.

An atom of the chemical element consists of a kernel and electronic shell. The kernel is the central part of the atom in which almost all of its mass is concentrated. Unlike electronic shell, the kernel has a positive charge.

You will need

Atomic number of the chemical element, the law of Molos

Instruction

Thus, the charge of the nucleus is equal to the number of protons. In turn, the number of protons in the core is equal to the atomic number. For example, the atomic number of hydrogen - 1, that is, the hydrogen core consists of one proton has +1 charges. Atomic sodium number - 11, the charge of its kernel is +11.

With the alpha-decay of the kernel, its atomic number decreases by two by emitting the alpha particle (the nuclei of the atom). Thus, the number of protons in the kernel, which experienced the alpha decay, is also reduced by two.
Beta decay can occur in three different types. In the case of the breakdown of "beta-minus", the neutron turns into a proton when emitting an electron and antineutrino. Then the nucleus charge increases per unit.
In the case of the breakdown of "beta-plus", the proton turns into a neutron, a positron and an input, the nucleus charge decreases by one.
In the case of electronic capture, the nucleus charge also decreases per unit.

The nucleus charge can also be determined by the frequency of the spectral lines of the characteristic radiation of the atom. According to the law of Mosley: SQRT (V / R) \u003d (Z - S) / n, where V is the spectral frequency of the characteristic radiation, R is permanent Ridberg, S - constant shielding, N is the main quantum number.
Thus, z \u003d n * sqrt (V / R) + s.

Video on the topic

Sources:

how the kernel charge changes

When creating theoretical and practical work on mathematics, physics, chemistry, a student or schoolboy faces the need to insert special characters and complex formulas. Having a Word application from the Microsoft office package, you can dial the electronic formula of any complexity.

Instruction

Click the Insert tab. Find the right π, and next to the inscription "Formula". Click on the arrow. A window appears in which you can choose a built-in formula, for example, a square equation formula.

Click on the arrow and on the top panel will appear a variety of characters that you may need when writing specifically this formula. By changing it as you need, you can save it. From now on, it will fall out in the list of embedded formulas.

If you need to transfer the formula B, which later needs to be placed on the site, then click on the active field with it right-click and select not professional, but a linear method. In particular, the entire square equation in this case will take the form: x \u003d (- b ± √ (b ^ 2-4ac)) / 2a.

Another version of writing an electronic formula in Word is through the designer. Hold the Alt and \u003d keys at the same time. You will immediately have a field for writing a formula, and the designer will open at the top panel. Here you can choose all signs that may be needed to record equations and solve any task.

Some linear recording characters can be an incomprehensible reader unfamiliar with computer symbolism. In this case, the most complex formulas or equations make sense to preserve in graphical form. To do this, open the most simple graphics editor Paint: "Start" - "Programs" - "Paint". Then increase the scale of the document with the formula so that it takes the entire screen. It is necessary that the preserved image has the greatest permission. Press PRTSCR keyboard, go to Paint and press Ctrl + V.

Cut everything too much. As a result, you will have a high-quality image with the desired formula.

Video on the topic

Under normal conditions, the atom is electrically neutral. In this case, the atom core consisting of protons and neutrons is positive, and electrons carry a negative charge. With an excess or disadvantage of electrons, the atom turns into an ion.

Instruction

Everyone has its own nuclear charge. It is the charge that determines the element number in the periodic system. So, the kernel of hydrogen +1, helium +2, lithium +3, +4, etc. Thus, if the element is known, the charge of the nucleus of its atom can be determined from the Mendeleev table.

Since under normal conditions, the atom is electrically neutral, the number of electrons corresponds to the charge of the atom nucleus. Negative compensated for a positive kernel charge. Electrostatic forces hold electronic clouds near the atom, which ensures its stability.

When exposed to certain conditions, an atom can take electrons or attach additional to it. If you take an electron from an atom, the atom turns into a cation - a positively charged ion. Under the excess number of electrons, the atom becomes an anion - a negatively charged ion.

We find out how to make an electronic formula of the chemical element. This question is important and relevant, as it gives an idea not only about the structure, but also on the intended physical and chemical properties of the atom under consideration.

Rules of compilation

In order to create a graphical and electronic formula of the chemical element, it is necessary to have an idea of \u200b\u200bthe theory of the structure of the atom. Let's start with the fact that there are two main components of the atom: core and negative electrons. The kernel includes neutrons that do not have charge, as well as protons with a positive charge.

Correcting, how to make and determine the electronic formula of the chemical element, we note that in order to find the number of protons in the core, the periodic system of Mendeleev will be required.

The number of the element in order corresponds to the number of protons located in its kernel. The number of the period in which the atom is located, characterizes the number of energy layers, are located on which electrons.

To determine the number of neutrons, devoid of electric charge, it is necessary from the relative mass of an element atom from the value, to take its sequence number (number of protons).

Instruction

In order to understand how to make an electronic formula of the chemical element, we consider the rule of filling with negative particles with a sublevel formulated by Clackovsky.

Depending on how free orbitals have free energy, a number characterizing the sequence of filling in electrons by electrons are compiled.

Each orbital contains only two electrons, which are arranged by anti-parallel spins.

In order to express the structure of electronic shells, graphic formulas are used. What do the electronic formulas of atoms of chemical elements look like? How to make graphic options? These issues are included in the school chemistry course, so we will stop on them.

There is a certain matrix (base), which is used in the preparation of graphic formulas. For S-orbitals, only one quantum cell is characterized, in which two electrons are opposite to each other. They are graphically indicated by arrows. For p-orbitals, three cells are depicted, each is also located two electrons, or the orbitals are located ten electrons, and F is filled with fourteen electrons.

Examples of electronic formulas

We will continue the conversation on how to make an electronic formula of the chemical element. For example, you need to make a graphical and electronic formula for the manganese element. First, we determine the position of this item in the periodic system. It has 25 sequence number, therefore, 25 electrons are located in the atom. Manganese is an element of the fourth period, therefore, he has four energy levels.

How to make an electronic formula of the chemical element? Record the sign of the item, as well as its sequence number. Using the rules of Clakovsky, distribute electrons by energy levels and sublayers. We consistently have them on the first, second, as well as the third level, entering two electrons into each cell.

Next, we summarize them, getting 20 pieces. Three levels are fully filled with electrons, and only five electrons remain on the fourth. Given that for each type of orbital it is characterized by its energy supply, the remaining electrons distribute on 4S and 3D sublayer. As a result, the finished electron-graphic formula for the manganese atom has the following form:

1S2 / 2S2, 2P6 / 3S2, 3P6 / 4S2, 3D3

Practical value

With the help of electron-graphic formulas, you can clearly see the number of free (unpaired) electrons that determine the valence of this chemical element.

We offer a generalized actions algorithm, with which the electron-graphic formulas of any atoms located in the Mendeleev table can be generated.

First of all, it is necessary to determine the number of electrons using the periodic system. The digit of the period indicates the number of energy levels.

Belonging to a specific group is associated with the number of electrons located on the outdoor energy level. Subdimo levels on the tap, fill them with the rule of Clakovsky.

Conclusion

In order to determine the valence capabilities of any chemical element located in the Mendeleev table, it is necessary to make an electron-graphic formula for its atom. The algorithm given above will cope with the task, determine the possible chemical and physical properties of the atom.