What is an E-nag?

In chemical reactions, the outer electrons of an atom generally change. For the sake of simplicity, black dots "." And crosses "x" are often used around the symbol of an element to indicate the outermost electron of an element atom. The expression of matter is called electronic. However, the electronic formula of the classic 8-carat body learned in middle school belongs to an outdated theory , and can only be used to represent a small part of the substances formed by the main group elements. Structure of common substances.

[diàn z shì]

Can be expressed electronically

1. No matter what kind of particles, the electronic formula is composed of atoms as the basic unit, and no corner codes or even coefficients can appear.

2. The electronic formulas of the atoms that make up various particles must strive for uniformity and symmetry. The stable 8-electron structure is usually expressed as four pairs of electrons (usually a pair of electrons above, below, left, and right of the element symbol.).

3. The electronic version of the classic 8-body body learned in middle school is an outdated theory and can only be used to represent a small part of

   There are certain limitations when electronically expressing the structure of a substance, for example; O ₂ (two three-center bonds); ozone (three-center four-electron bonds); superoxide (three-electron bonds); odor oxide (three-center) Five-electron bond); carbon dioxide, nitrous oxide, azide N ^3- (three-center four-electron bond) ... and so on, all of which cannot be expressed electronically in structure.

   That's why we say that the electronic type is more limited and can only describe the structure of a small number of substances. Structures in the true sense cannot be represented electronically.

   Here we need to note that CO ₂ is a compound that cannot be explained electronically (there is a large bond), and the description of the structure of CO _{2 in} secondary schools is completely wrong. Because experiments have shown that the length of the CO bond in carbon dioxide is between carbon monoxide (a typical triple bond) and carbonyl (

   (1) Anions and complex cations should be enclosed in parentheses, and the number of charges should be indicated. Simple cations are indicated by the element symbol plus the charge.

   (2) Pay attention to the fact that atoms in chemical bonds are directly adjacent.

   (3) Electronic pairs that have not participated in the formation of bonds must not be missed. ^[1]