How do you determine the number of electrons? How to judge the number of electrons

First of all, it is necessary to know which elements have changed their valency, the process of valency change is that the electrons have been transferred, and then the gain and loss of electrons is determined, and the valency of the elements is marked, and the valency of the elements is increased before and after the reaction, and the electrons are obtained when the valency is increased, and the electrons are obtained when the valency is reduced, such as the reaction of 2-valent iron element to generate 3-valent iron element, then the valency is increased and the electrons are lost.

Finally, the number of electrons gained and lost is determined, taking iron as an example, 2 valence to 3 valence, the difference is one electron, then we say that he has lost one electron. An increase in valency of 2 results in the loss of 2 electrons.

However, it should be noted that the above is a simple case, and the complex situation also depends on the coefficient in front of the element, if the coefficient in front of the 2 valence iron is 3, and the coefficient of the product 3 valence iron is 2, then in fact, only 2 of the 3 2 valence iron are converted into 3 valence iron, (a 2 valence iron generates a 3 valence iron and loses an electron, then 2 2 valence iron to generate 2 3 valence iron should lose 2 electrons) then the number of electrons lost is 2 times 12 of them is the actual number of people participating in the reaction, and 1 is the change value of valence! Hope!

Just calculate the sum of the electrons carried by all the atoms that make up the molecule. Number of electrons = number of nuclear charges = number of protons = number of atomic numbers.

A nitrogen atom has 7 and a hydrogen atom has 1 electron, 7+3=10

1. There are two electrons in a double-bonded rock, and the electrons of a conjugated system depend on the number of electrons provided by each atom involved in the conjugation. For example, ch2=chch=ch2, electron is 4; ch2=chcl, the number of electrons is 4; ch2=chch=o, the number of electrons is 4, and the number of electrons of benzene is 6; The number of electrons of phenol is 8 and so on.

2. The so-called electron is the electron that uses the p orbital electrons to participate in bonding, and is divided into small bonds and delocalized large bonds.

See carbon-carbon double bond alone.

It's a small bond, and it's the electrons that participate in the bonding. It is generally seen that the alternating single and double bonds of carbon and carbon are large bonds, and it is also electrons that participate in bond formation.

3. Generally speaking, if there is only one pair of electrons between two atoms forming a bond, a coarse covalent bond is formed.

is a single key, usually always a key.

If the covalent bond between atoms is a double bond, it consists of a bond and a bond. If it is a triple bond, it consists of one key and two keys. Each bond has two electrons.

Think of it this way, each double bond has 2 electrons, and every triple bond has 4 electrons.

The electronic configuration of the outermost shell of the element changes periodically:

Element 2. There is only one electron shell, and in period 1, the number of electrons in the outermost shell increases. Element 1 hydrogen has only one electron, and the outermost electron is also 1; Element 2 helium has two electrons, and the outermost electron is also 2.

Element 10. The first shell of an element can only have 2 electrons, so elements 3-10 have two electron shells, and in the second period, the number of electrons in the outermost shell increases from 1 to 8. For example, element 7 nitrogen has 7 electrons, 2 in the first shell, and 5 in the second and outermost shell. Element 8 has 8 electrons.

There are 2 in the first layer, 6 in the outermost layer (8-2=), and so on.

18 elements. The outermost electrons of an element cannot exceed 8, so elements 11-13 have three electron shells, and in the third period, the number of outermost electrons increases from 1 to 8. For example, element 12 magnesium has 2 electrons in the first shell, 8 electrons in the second shell, and (12-2-8=) 2 electrons in the outermost shell.

4. The electrons in the subouter shell of the element do not exceed 18 electrons, and the penultimate layer does not exceed 32.

The number of electrons is equal to the number of electrons, specifically the number of electrons outside the nucleus of an atom or ion.

The number of electrons is the number of electrons. Electrons are an elementary particle.

In chemistry, the number of electrons generally refers to the number of electrons outside the nucleus of an atom or ion, while the number of electrons in the outermost shell determines the chemical properties of an element.

For example, noble gases.

The outermost electron number of atoms reaches a stable structure, and their chemical properties are stable, while the outermost electron number of metal and non-metal atoms does not reach a stable structure, so their chemical properties are active.

Extranuclear electron configurationApplication of knowledge

1. When the number of nuclear charges is the number of electrons outside the nucleus, the particle is an atom.

If the number of outermost electrons in the shape is 8 (2 for helium), the atom is a noble gas atom with a relatively stable structure and generally does not undergo chemical changes.

If the number of bright electrons in the outermost shell is less than 4 at this time, the atom is a metal atom (except hydrogen, helium, and beryllium), and the world cavity is easy to lose the outermost electrons in the chemical change, so that the subouter shell becomes the outermost layer and reaches a relatively stable structure of 8 electrons, forming a cation.

If the number of electrons in the outermost shell is greater than or equal to 4 at this time, the atom is a non-metallic atom, and it is easy to obtain electrons in the chemical change and make the outermost shell reach a relatively stable structure of 8 electrons to form an anion.

2. When the number of nuclear charges > the number of electrons outside the nucleus, the particle is a cation; When the number of nuclear charges < the number of electrons outside the nucleus, the particle is anionic.

3. Valency of elements.

Number Number of charges carried by ions Number of protons Number of electrons, positive and negative valency and the sign of charge of ions ( , same.

1. The number of electrons of an atom is equal to the number of its nuclear charge, i.e. in the periodic table.

Ordinal numbers in . The cation is the number of nuclear charges minus the electric charge, and the anion.

It's a gaki oak.

2. In an atom, the number of electrons outside the nucleus is equal to the number of protons in the nucleus is equal to the number of nuclear charges and the number of atomic numbers.

3. In a molecule, the number of electrons is the sum of the number of electrons carried by each atom.

4. In ions, the cation is formed by the atom losing electrons, while the anion is the analysis and calculation of the electron formation obtained by the atom.

A double bond has two electrons, and the number of electrons in a conjugated system depends on the number of electrons provided by each atom involved in the conjugation. As.

ch2=chch=ch2, electron is 4; ch2=chcl, the number of electrons is 4; ch2=chch=o, the number of electrons is 4, and the number of electrons of benzene is 6; The number of electrons of phenol is 8 and so on.

The atoms on the aromatic ring contribute one electron when participating in a double bond (bond) (resonance formula is another matter), and the saturated atom with lone pairs of electrons contributes two electrons. For example, -pyranone, its carbon atom participates in the carbonyl group, but because the resonance formula is very stable, in fact, a pair of electrons of the carbonyl group is all on the side of the oxygen atom and does not contribute to the pyran ring.

Aromatic hydrocarbons do not necessarily contain benzene rings. An important rule for predicting molecular aromaticity for non-aromatic hydrocarbons is the shock rule. The rule suggests that molecules with (4n+2) electrons (where n is an integer greater than or equal to zero) may have special aromatic stability for fully conjugated, single-ring, planar polyenes.

With the advent of magnetic resonance experiments, it has played an important role in determining whether a compound has aromativity, and the nature of aromaticity has been further understood. Therefore, the broader meaning of aromaticity is that the molecule must be a coplanar closed conjugated system; The keys are averaged; The system is relatively stable (with large resonance energy); From the experimental point of view, it is easy to have an electrophilic substitution reaction on the ring, and it is not easy to have an addition reaction. In the magnetic field, it can produce a magnetic circulation; Microscopically, the number of electrons conforms to the 4n+2 rule.

The above was searched on the Internet.

I'm referring to the method when I wrote the Lewis formula, first calculate the total number of electrons in the valence shell, then subtract the number of electrons of the bond, and the rest is the number of electrons. For example, there are a total of 6+6 4=30 valence shell electrons, minus 6 c-h and 6 c-c bonds, a total of 12 2=24 electrons, and the remaining 6 electrons is the number of electrons. Is this approach advisable?

The number of electrons is not equal to 4n+2, such as benzene, but there are some hydrocarbons that conform to this structure but are not aromatics.

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