Junior High School Chemical Learning -Physical Nature

1. Concept: The nature of the represented by chemical changes is required.

2. area

(1) Color (colorless, reddish brown, yellow -green, etc.), odor (tasteless, aroma, irritating, etc.), state (solid, liquid, gas).

(2) The process of melting points and boiling points: The process of material changes from solid state to liquid state is called melting, and the melting temperature of the material is called melting point; the process of material changes from liquid to gaseous is called gasification, and the temperature when liquid gasification boils is called boiling point. (The height of the boiling point of the liquid is related to the atmospheric pressure. The lower the air pressure, the lower the boiling point)

(3) dissolving (generally refers to water -soluble, including insoluble, slightly soluble, soluble, easy to ongen, etc.), volatility (the boiling point of this substance is often low, such as hydrochloric acid, nitric acid, etc.).

(4) Conductivity, thermal conductivity, and ductility (often the pioneering of metals).

(5) Hardness (the properties of solids), density (the mass of the volume of a certain material unit is called the density of this substance. For example, the density of water is 1.0g/cm3).

3. The physical properties of material are often intuitive and easy to recognize. In the process of physical changes in material, we can understand the physical nature of their physical properties. The physical properties of matter determine physical changes, and the physical changes of matter can reflect their physical properties.

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