What are the laws in the periodic table?

The periodic law can be expressed as the periodic law of periodic change of the properties of an element with the increasing number of atomic numbers. As the atomic number increases, the properties of the elements show a periodic and gradual change law:

In the same period, the metallicity of the element decreases from left to right and the non-metallicity increases from left to right, and in the same family, the metallicity of the element increases from top to bottom and the non-metallicity decreases from top to bottom; During the same period, the highest positive valence oxide of the element increased from left to right (except for those without positive valence), and the lowest negative valence oxide gradually increased from left to right. The elements of the same family are similar in nature. In the same period of the main group of elements, the atomic radius decreases with the increase of atomic number. In the same family, the atomic radius increases with the increase of atomic number.

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<> 1. Atomic radius.

In the same period (except for noble gases), from left to right, as the atomic number increases, the radius of the atom of the element decreases;

In the same family, from top to bottom, the atomic radius of an element increases as the atomic number increases.

2. In the same cycle, from left to right, with the increase of atomic number, the highest positive valence of the element increases (from +1 valence to +7 valence), except for the first period, except for the O and F elements of the second cycle, the lowest negative valence refers to the increase (from -4 valence to -1 valence) except for the first cycle, because metal elements generally have no negative valence, so start from the A group. The sum of the absolute value of the most ** element and the absolute digging-value of the lowest price is 8

3. Metallic and non-metallic properties of elements.

In the same period, from left to right, as the atomic number increases, the metallicity of the element decreases and the non-metallicity increases; In the same family, from top to bottom, with the increase of atomic number, the metallicity of the element increases, and the non-metallicity decreases;

1 The law of gradual degeneration of elements and their compounds in the periodic table.

Atomic radius. 1) The atomic radius of the periodic elements (except the noble gas elements) decreases with the increasing atomic number, except for the first period;

2) The atomic radius of elements of the same group increases from top to bottom as the number of electron layers increases.

Elemental valence.

1) Except for the first period, from left to right in the same period, the highest positive valence of elements increases from alkali metal +1 to +7, and the negative valence of non-metallic elements increases from carbon group -4 to -1 (except for fluorine without positive valence and oxygen without +6 valence);

2) The highest positive and negative values of elements in the same main family are the same.

The melting point of an element.

1) With the increase of atomic number of elements in the same period, the melting point of the elemental element increases, and the melting point of the non-metallic element decreases.

2) From top to bottom, the melting point of the metal element composed of the elements decreases, and the melting point of the non-metal element increases.

The metallicity and non-metallic properties of the elements.

1) The metallicity of elements in the same period decreases from left to right, and the non-metallicity increases;

2) The metallicity of elements in the same main group increases from top to bottom, and the non-metallicity decreases.

The most ** acidity and alkalinity of oxides and hydrates.

The stronger the metallicity of the element, the stronger the alkalinity of the hydrate of its most ** oxide; The stronger the non-metallic nature of the element, the more acidic the most oxide socks or hydrates are.

Non-metallic gaseous hydrides.

The stronger the element non-metallic, the more stable the gaseous hydride. The stronger the non-metallic nature of the non-metallic elements in the same period, the more acidic the gaseous hydride aqueous solution is. The stronger the non-metallic nature of the non-metallic elements of the same main group, the weaker the acidity of the gaseous hydride aqueous solution.

Oxidation and reduction of elemental matter.

The stronger the metallicity of the general element, the stronger the reduction of its element, and the weaker the oxidation of oxygen ions of its oxides. The stronger the non-metallic nature of the element, the stronger the oxidation of its elemental substances, and the weaker the reducibility of its simple anions.

2.Inferring the regularity of the position of an element.

The law that should be kept in mind to determine the position of an element in the periodic table:

1) The number of periodic elements is equal to the number of electron shells outside the nucleus;

2) the ordinal number of the main group elements is equal to the number of electrons in the outermost shell;

3) To determine the number of families, it is necessary to determine whether it is a major group or a secondary group, and the method is to use the atomic number to gradually subtract the number of element species in each period, which can be determined by the final difference. The final difference is the family ordinal, when the difference is VIII group, when the difference is greater than 10, then subtract 10, and the final result is the family ordinal.

By: Beryu - Tong Sheng Level 1 2-23 19:08

The periodic table of chemical elements is arranged according to:

1. The right decreases in turn, and the upper Hu Sun increases in order to the bottom.

2. The periodic table has 7 periods and 16 families. Each horizontal row is called a cycle, and each vertical row is called a family (group VIII contains three columns). These 7 cycles can be divided into short cycles and long cycles).

3. In the same period, from left to right, the number of electrons outside the nucleus of the element is the same, the number of electrons in the outermost shell increases in turn, and the atomic radius decreases (except for group zero elements). The ability to lose electrons is gradually weakened, the ability to gain electrons is gradually increased, the metallicity is gradually weakened, and the non-metallic ability is gradually enhanced.

4. In the same family, from top to bottom, the number of electrons in the outermost shell is the same, the number of electrons outside the nucleus gradually increases, the atomic radius increases, the atomic number increases, the metallicity of the element increases, and the non-metallicity decreases.

The periodic table of chemical elements is a list of chemical elements sorted by their atomic weights from smallest to largest. The list is usually rectangular in shape, with spaces in some element cycles, so elements with similar characteristics can be grouped into the same family, such as alkali metal elements, alkaline earth metals, halogen elements, noble gases, non-metals, transition elements, etc. This makes the periodic table form elemental divisions, which can be divided into seven main families, 7 auxiliary households, and 0 households.

Because of its ability to accurately characterize various elements and their relationships, it is widely used in chemistry and other scientific fields as a very useful framework for analyzing chemical behavior.