Higher than the chemical periodic law of the change in valency

It can be simply understood that each cycle starts from the first element, and this law of gradual change appears. For example, the third cycle starts with sodium and has a maximum positive price of +1, magnesium +2, and aluminum +3......By analogy, the highest positive price of chlorine is +7, and the fourth cycle also has this gradual law from k, and the lowest secondary price can also be understood in this way.

And each element (oxygen.

Fluorine. No regular price) are satisfied:

The absolute value of the lowest side price + the highest positive price = 8

This law.

Hello. Valency of the element.

It can be based on the number of electrons in the outermost shell of the atom.

to judge. For example, from the third cycle, there is one electron in the outermost shell of NA, so the highest positive valence is +1 (no negative valence for metals).

Magnesium has 2 electrons in the outermost shell, then in the same way, when it loses electrons to become a magnesium ion, it loses the outermost two electrons and thus becomes +2

Generally, the outermost element below 4 electrons loses electrons and becomes positive when it forms ions, and the outermost 4 or more electrons, such as chlorine, have 7 electrons in the outermost shell, and an electron is obtained to form a stable structure, so that the outermost 8 electrons are in the outermost shell, but because the electrons are negative valence, chloride ions.

is -1 price. In short, the change in valency of an element is due to the change in the number of electrons in the outermost shell, and generally there are a few electrons in the outermost shell, which can show + valence.

Among them, fluorine and oxygen generally have no positive valence.

Let's take the third period element as an example, sodium has 1 electron in the outermost shell, so the highest positive valence is +1 valence, magnesium +2, aluminum +3, the highest positive valence of each element is equal to the number of outermost electrons, and the lowest negative valence is equal to the highest positive valence -8, but each period is gradually increasing whether it is the highest positive valence or the lowest negative valence.

The main valency of the same main family is the same, e.g. the main valency of group A is +1 valence and the main valency of group A is -1 valence.

In the same period, the highest positive price from left to right gradually increases, starting from the negative price, the negative price also gradually increases, and finally reaches 0 (rare gas).

For example: third cycle namgal

sipscl

ar.The highest positive price ranges from +1 of Na to +7 of Cl, with negative valence starting from Si, -4 of Si to -3 of P and -1 of Cl, and finally 0 of Ar

The valency of an element changes periodically with increasing atomic number. The highest valency of the main group elements in the same period increases from left to right. The valency of elements of the same group is basically the same; For most elements, their highest valency is equal to the ordinal number of the group in the periodic table in which they are located.

The main valence change law

In the same period, from left to right, as the atomic number increases, the highest positive valence of the element increases (from +1 valence to +7 valence), except for the first period, except for the O, F (O has no highest positive valence, F has no positive valence, except for OF2) elements of the second period;

The first cycle of the lowest negative valence increase (from 4 valence to 1 valence) is excluded, and since metal elements generally have no negative valence, they start from the A group.

The sum of the absolute value of the most ** element and the absolute value of the lowest price is 8, and the algebraic sum is one of the even numbers of 0, 2, 4, 6 (only for non-metals except o and f).

Valency

Valency is the property of an element when one atom of an element is combined with the atoms of another element. In general, the valence of valency is equal to the number of electrons gained and lost by each atom during compounding, that is, the number of electrons gained and lost when the element can reach a stable structure, which is often determined by the electronic configuration of the element, mainly the outermost electron configuration, and of course may also involve the substable structure composed of sublayers that the subouter shell can achieve.

During the displacement reaction, the element changes from elemental to compound, and from compound to elemental, and the valency must change.

During the metathesis reaction, the valency of the elements remains unchanged.

During the chemical reaction, the element changes from 0 valence to the valence state of the corresponding compound.

When a decomposition reaction occurs, it is the opposite change of the chemical reaction.

In addition, when the element reacts with other substances, the valency must change.

1) There are positive and negative valences.

2) Oxygen is usually permeated with -2 valence.

3) Hydrogen usually shows +1 valence.

4) When metal elements and non-metallic elements are combined, the metal elements show positive valence, and the non-metallic yuan banquet element shows negative valence (generally speaking, the positive price is written in front of the shouting potato, and the negative price is written behind).

5) Some elements can show different valencies in the same substance.

6) The algebraic sum of positive and negative valencies in a compound is 0

7) The valency of an element is a property exhibited by the atoms of an element when forming a compound, so in an elemental molecule, the valency of an element is 0

In the periodic table:

Same period: As the number of nuclear charges increases, the atomic radius gradually decreases (except for noble gas atoms). For example: third cycle: Na>mg>Al>Si>P>S>Cl.

The same main group: the atomic radius gradually increases as the number of nuclear charges increases. For example:

The periodic table of group ia:h chemical elements is a list of chemical elements sorted from smallest to largest according to their atomic number. The list is generally rectangular in shape, with spaces in the period of some elements, so that elements with similar characteristics are grouped into the same family, such as alkali metal elements, alkaline earth metals, halogen elements, rare gases, etc.

This results in the periodic table forming an elemental partition with seven primary families, seven secondary groups, and zero families.

The main valency of the same main family.

Same, e.g. The main valencies of the A group are all +1 valences and the main valencies of the A group are all -1 valence.

In the same period, the highest positive price from left to right gradually increases, starting from the negative price, the negative price also gradually increases, and finally reaches 0 (rare gas).

For example: the third cycle na mg al si p s cl arThe highest positive price ranges from +1 of Na to +7 of Cl, with negative valence starting from Si, -4 of Si to -3 of P and -1 of Cl, and finally 0 of Ar

Let's take the third period element as an example, sodium has 1 electron in the outermost shell, so the highest positive valence is +1 valence, magnesium +2, aluminum +3, the highest positive valence of each element is equal to the number of outermost electrons, and the lowest negative valence is equal to the highest positive valence -8, but each period is gradually increasing whether it is the highest positive valence or the lowest negative valence.

That is, the more the number of charges of an element in the same period, the higher the valence state. The valence state is the same as that of the main family.

This is the law, the law we get from the known ** data, and summarize the periodic law from the time!