How to find the valency of an atom according to covalent bond in organic chemistry

To determine the valency in organic matter, we must first clarify their bonding mode, after knowing the bonding method, we must understand the electronegativity of the element (the ability to attract electrons is called electronegativity, and strong electronegativity means that the ability to attract electrons is strong), and then all the electrons of the covalent bond are counted to the elements with strong electronegativity, so that the "electric electricity" of the element to be found is its valency value, and the positive and negative are determined by the positive and negative charges.

For example, CH4, C and H form 4 C-H bonds, because the attraction of C to electrons is greater than H, so all the shared electrons in C-H are counted as C, so there are 8 electrons around C, 4 more than its initial 4 electrons, so C is negatively charged, and the electric amount is 4, so C is 4 valence.

Valency. When the elements are combined with each other, the ratio of the number of reactant atoms is always constant. For example, one sodium must be bound to one chlorine. And one mg must be combined with two. If it is not for this number ratio, it cannot be made to constitute an ionic compound.

anions and constituent covalent compounds.

The outermost electron shell of a molecule's atom.

Become a stable structure. It is not possible to form stable compounds. And because the atom is the smallest particle that cannot be separated in a chemical reaction, when the elements are combined with each other to form a certain compound, the number of atoms of each element must be a certain simple integer ratio.

The concept of valency comes from this, then the number of atoms of an element that are mutually combined determines the valency of this element, and the valency is set to facilitate the representation of the number of atoms that are mutually combined. When learning valency, you should be aware of the rules for elemental valency in compounds.

In addition, it is stipulated that in elemental molecules, the valency of elements is zero, and the algebraic sum of positive and negative valencies of both ionic compounds and covalent compounds is zero.

The valency is expressed in +1, +2, +3, -1, -2 ...... for positive and negative valence0 and so on should be marked in the element symbol.

directly above; When learning, you should memorize the valency of h(+1), o(-2), na(+1), k(+1), mg(+2), al(+3), fe(+2,+3), s(+4,-2,+6), cl(-1), and then use the algebraic sum of positive and negative valency to 0 according to the valency of common elements to calculate the valency of unfamiliar elements.

Three. Valency of common elements.

Monovalent hydrochloride, sodium chloride, potassium, silver, divalent oxygen, calcium, barium, magnesium, zinc, trialuminum, silicon, pentavalent phosphorus, it is not difficult to talk about price change, copper, one, two, iron, two, three.

246 sulfur 24 carbon .

If the oxidation is strong, it shows negative valence. Significant positive price with strong reductivity. That's it, it's simple.

I'm dizzy, organic chemistry generally doesn't care about valency. (carbon is generally +2 price).

The covalent bonds of the organic compounds are described as follows:

Covalent bond is a kind of chemical bond, two or more atoms use their outer electrons together, ideally to reach a state of electron saturation, thus forming a relatively stable chemical structure, like this by several adjacent atoms through the sharing of electrons and the formation of a strong interaction between the shared electrons is called a covalent bond.

Its essence is that after the overlapping of atomic orbitals, there is a high probability of electron interaction between two nuclei and between two nuclei.

In the process of forming covalent bonds, because the number of unpaired electrons that each atom can provide is certain, after an unpaired electron of an atom is paired with the unpaired electrons of other atoms, it can no longer be paired with other electrons, that is, the total number of covalent bonds that can be formed by each atom is a certain amount, which is the saturation of covalent bonds.

The saturation of covalent bonds determines the quantitative relationship between various atoms when they form molecules, which is one of the intrinsic reasons for the law of fixed ratio.

Except for the s orbital which is spherical, other atomic orbitals have their fixed extension direction, so when the covalent bond is formed, the orbital overlap also has a fixed direction, and the covalent bond also has its directionality, and the direction of the covalent bond determines the configuration of the molecule. The factor affecting the directionality of the covalent bond is the direction of orbital extension.

When learning ionic bonds and covalent bonds, that is, when learning the second compulsory chemistry in high school, you only need to master the following rules:

1. Reactive metals (generally referred to as IA, IIA) and active non-metals (generally referred to as VIA, VIIA) are combined to form ionic bonds, such as: sodium chloride NaCl, potassium oxide K2O, etc.;

2. The chemical bonds formed between non-metals and non-metals are covalent bonds. Ammonium salts, inactive metals and non-metals between ALCL3 and BECL2 are excluded.

For example: CO2, NH3, H2O, SO2, etc.;

When studying Chemistry Elective 3, you need to judge ionic bonds and covalent bonds based on electronegativity.

It is generally believed that if the electronegativity difference between the atoms of two bonding elements is greater than that, an ionic bond is usually formed between them; If the difference in electronegativity between the atoms of two bonding elements is less, a covalent bond is usually formed between them.

For example: the electronegativity of Al is 4, and the difference between the electronegativity of chlorine and aluminum = , so it is an ionic bond;

This kind of problem actually needs you to think about it carefully, and you can summarize it yourself after understanding

C—C bonds: saturated hydrocarbons: x carbon atoms in chains: x-1 bonds; ring-shaped x bonds;

Monoolefins: x carbon atoms in chains: x bonds; Ring x+1 keys;

Diolefins or alkynes: x carbon atoms in chains: x+1 bonds; Ring x+2 keys;

C—H bond: Each H atom can only form one bond, so, there are y H atoms to form y bonds;

In addition, for compounds in general, there is such a rule:

1) The valency of an element atom is generally equal to the number of covalent bonds formed by the atom; This is not the case with non-polar bonds.

2) The number of atoms forming covalent bonds in a monoprime is generally equal to the number of single electrons in the outermost shell of its atoms.

Chemical bonds can be divided into ionic and covalent bonds.

Ionic bonds are found in most strong bases, salts, and metal oxides.

When a chemical reaction occurs, the chemical bonds are broken.

There are many forms of ionic bond breaking, such as sodium chloride crystals dissolved in water, and ionic bond breaking between chloride ions and sodium ions. Another example is the reduction of copper oxide by hydrogen, which destroys the copper oxygen ion bonds.

A distinction should be made between ionic and covalent bonds. The difference in the definition of ionic bond and covalent bond is the difference in electronegativity between two atoms. The difference between the electronegativity of the two atoms is greater than that, forming an ionic bond; Otherwise, a covalent bond is formed.

If the two atoms are the same, a non-polar covalent bond is formed; Otherwise, a polar covalent bond is formed.

Metallic elements don't necessarily form ionic bonds! Classical complexes such as [CO(NH3)6]Cl3 are good examples. There are also metal metal bonds in metal clusters, etc., which are all counterexamples.

Non-metallic elements are not necessarily covalent bonds! It's like NH4NO3.

The purpose of bonding is to stabilize the electronic structure of each atom and thus reduce the energy of the system. From the perspective of middle school, covalent bonds are used to achieve their purpose by sharing electrons, and their role is complex in nature. Typical ones are Cl2, O2, H2O, etc.

The ionic bond is achieved through the gain and loss of electrons, such as NaCl, KCL, CSF, etc., and its effect is essentially the Coulomb force between anion and ion. However, ionic and covalent are not completely opposites, but often co-exist, but there is a primary and secondary relationship. In CSFs where electronegativity (a measure of an element's ability to gain electrons) differs the most, there is still covalence that cannot be ignored.

The ionic bonds involved in secondary school are all typical ionic bonds, and their covalentness is not discussed. Therefore, it can be seen that A loses electrons and becomes a cation with a stable shell structure, and B gains electrons to become a stable anion, and this electron B will not, and A does not want to share. To emphasize that this electron is b, use [

Bracket b.

1 All covalent bonds (covalent

bonds) is a type of chemical bond in which two or more atoms share their outer electrons to reach electron saturation under ideally conditions, thus forming a relatively stable and strong chemical structure called a covalent bond. The so-called covalent bond refers to the chemical bond formed between atoms due to the overlap of the atomic orbitals of bond-forming electrons. Unlike ionic bonds, atoms that enter the covalent bond do not show electrical properties outwards because they do not gain or lose electrons.

The strength of the covalent bond is stronger than the hydrogen bond and is not much different from the ionic bond or even stronger than the ionic bond.

The valency of carbon dioxide carbon is +4 valence, and calcium oxide is +2 valence.

Those with strong oxidation are negative and those with strong reduction are positive.

The valency of the reducing agent increases, electrons are lost, and they are oxidized; The valency of the oxidant decreases, electrons are obtained, and they are reduced.

From the main group, from top to bottom, the reducibility of metals gradually increases, and the oxidation of non-metals decreases gradually.

From left to right on the horizontal axis, the metal reducibility gradually decreases, and the non-metal oxidation gradually increases, except for group 0.

The outermost electrons of the atom are greater than 4, which is oxidizing, and the more electrons there are, the stronger the oxidation. The outermost electrons of the atom are less than or equal to 4, which is reductive, and the smaller the number of electrons, the weaker the reductivity.

The covalent bond electron pair is negative when it shifts to that side, the ionic bond is similar, and the more electrons in the outermost shell of non-metals, the smaller the nucleus (the smaller the ordinal number), the stronger the ability to attract electrons; In general, the lower the outermost electrons of a metal, the larger the nucleus (the larger the ordinal number) and the weaker the ability to attract electrons.

Oxygen is generally negative bivalent, metals are generally positive, and calcium oxide is +2 valence.

The oxygen in carbon dioxide is electronegative, and the oxygen -2 valence, carbon is +4 valence, how can it be -4.