Energy law: from near to far from the nucleus, from low to high energy

Quantity rule: Each layer can accommodate up to 2 electrons, and the outermost layer does not exceed 8 (when there is only one layer, no more than 2)

A chemical bond formed by sharing electron pairs between atoms (atoms have different abilities to attract electrons, so the electron pairs are offset)

The same non-metal atoms have the same electronegativity and the electron pairs do not shift - non-polar covalent bond

Different non-metal atoms have different electronegativities, and electron pairs tend to attract atoms with strong electron ability (strong electronegativity) - polar covalent bonds

Atom: Arrange all the outermost electrons of the atom around the element symbol

Metal cations: ion symbol

Non-metal anions: Mark the obtained electrons around the element symbol, surround the symbol with [ ], and mark the number of charges in the upper right corner

Covalent compound (element): When writing, write the shared electron pair between the two atoms, and the unbonded electrons of each atom should also be written.

Ionic compounds: Write the electronic formulas of anion and cation respectively.

|Valence| Number of electrons in the outermost shell of an atom = 8

Diatomic element: number of electrons in the outermost shell of the atom, chemical health number = 8

The difference in atomic numbers of short-period elements = the difference in group numbers

When two elements are distributed on the same side of the transition element, the difference in atomic number = the difference in group number When the oxygen element is distributed on both sides of the transition element, the difference in atomic number of the elements in the fourth or fifth period = the difference in group number 10, and the difference in atomic number of the elements in the sixth and seventh periods = the difference in group number 24

The difference in atomic number between Group IIA and Group III in the fourth and fifth periods is 11, and in the sixth and seventh periods it is 25

For Group IA elements, as the electron shell increases, the atomic numbers differ by 2, 8, 8, 18, 18, and 32.

For elements in Group IIA and Group 0, as the number of electron shells increases, the atomic numbers differ by 8, 8, 18, 18, and 32.

For elements in groups IIIA to VII, as the number of electron shells increases, the atomic numbers gradually change from 8, 18, 18, 32, and 32.

Cycle ___, family ___

Inference method

r (anion)>r (atom)>r (cation)

r (low-valent cation) > r (high-valent cation)

Same cycle

Same main group: from top to bottom, the corresponding atomic radius and ionic radius gradually increase

Different particles with the same atomic structure: the greater the nuclear charge, the smaller the ionic radius

The more easily an atom loses electrons, the stronger its metallicity (it has nothing to do with the number of electrons lost by the atom)

In the metal activity sequence table, the higher the position of the metal, the stronger the metallicity.

The more violent the reaction between the element and water or non-oxidizing acid, the stronger the metallicity.

The stronger the elemental reducing property or the weaker the cationic oxidizing property, the stronger the metallicity.

The stronger the alkalinity of the hydrate corresponding to the highest valence oxide, the stronger the metallicity.

The position of an element in the periodic table: Elements to the left or below are more metallic

The easier it is for an atom to obtain electrons, the stronger its non-metallic property (it has nothing to do with the number of electrons obtained by the atom)

The easier it is to combine with H, the more stable the gaseous hydride is and the stronger its non-metallic property.

The stronger the oxidizing property of the element or the weaker the reducing property of the anion, the stronger the non-metallic property.

The stronger the acidity of the hydrate corresponding to the highest valence oxide, the stronger the non-metallic property.

The position of an element in the periodic table: Elements to the right or above are more non-metallic

Number of protons in an atom = Number of nuclear charges = Number of electrons outside the nucleus = Atomic number

The number of electron shells = period number; the number of electrons in the outermost shell = group number

Ion charge number

Gradient changes in the radius of particles with the same period and the same main group

Gradient rules and similarities of metallic and non-metallic properties of elements

Oxidizing and reducing properties of C, N, O, S, Cl, Na, Al and other elements and their compounds

Physical properties of common substances