Electronic configuration of elements
The electronic configuration of elements is an important concept in chemistry. Electron configuration modes of different elements are different, such as K [Ar]4s 1, Cr [Ar]3d54s 1, Cu [Ar]3d 104s 1. In addition, the electronegativity of Se, As and Br increases in turn.
Minimum energy principle and hunter's law
The lowest energy principle and Hunter's law are the basic principles in chemistry. The electronic configuration of the element 1s 222 p 63d 10 is the electronic configuration of the inert gas neon, which follows the principle of minimum energy and Hunter's law.
Melting point and boiling point of matter
The melting point and boiling point of a substance are important indicators of its properties. The higher the relative molecular mass of substances with similar composition and structure, the greater the Van der Waals force and the more energy needed, so the higher the melting point and boiling point.
Structure of compound
The structure of compounds is an important concept in chemistry. For example, GaBr3 is sp2 hybrid, similar to BCl3, forming a planar triangular structure. This structure has the symmetry of regular triangle and double cone, and the elements intersect at one point, so it is nonpolar.
Calculation of crystal
The calculation of crystals is an important content in chemistry. For example, the coordination number of Ca2+ is 6, and the side length of a cell can be calculated by the formula: side length = [224/(Na)] 1/3. Each cell contains 4 Cao, and the density A can be calculated by the following formula: a=56*4/(NV).