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chemical wiki for the best echemi chemicals

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刘晓栋
chemical wiki for the best echemi chemicals

Chemical wiki: Other concepts Salting out, denaturation, weathering, deliquation, combustion, double salt, fractionation, crystallization, extraction, law of conservation of mass, electrochemistry related concepts, etc. Contents of this chapter Part 1 Composition, properties and classification of substances Part 2 REDOX reactions Part 3 Chemical terms Part 4 Common metrology Part 5 Solutions and colloid Part 6 Chemical reactions and energy 2


Fundamentals of chemistry one. Atomic nuclei A. Quantitative relation: number of protons in the nucleus = number of electrons in the nucleus b, electrical relation: atom: nuclear charge = number of protons in the nucleus = number of electrons in the nucleus Cationic: number of protons in the nucleus > number of electrons in the nucleus anion: number of protons in the nucleus < number of electrons in the nucleus c, mass relation: mass number (A) = number of protons (Z) + number of neutrons (N) properties of two particles 


1. Molecules are small particles that are small in size: if you compare the size of a water molecule to a ping-pong ball, it's like comparing a ping-pong ball to the Earth. -26 Small mass: Take water molecules as an example, the mass of 1 water molecule is about 3×10kg. Molecules are small and light, but they are real. 


2. Molecules are always in motion There are many examples of molecular motion. Wet clothes dry when they are hung; You can smell the flowers from a distance; When a lump of sugar is placed in water, the sugar disappears and the water becomes sweet, all as a result of the constant movement of molecules. The movement of molecules is related to temperature, the temperature is high, the molecular movement is fast; Low temperature, slow molecular motion. 


1, Molecules Molecules are the smallest particles that maintain the chemical properties of substances. Use the molecular point of view to distinguish between the mixture and the pure matter (composed of molecules) the mixture of pure matter to distinguish macro: 1, by two or more substances mixed into macro: 


1, composed of a substance, there is a fixed composition of 1 2, each substance still maintains the original chemical properties of 2, there is a certain physical and chemical properties of microscopic: the mixture contains a variety of molecules microscopic: Only a molecule is different in the pure pure mixed contact pure, mixture separation and purification of 2, atom is the smallest particles of chemical reaction. Third, the difference and connection of molecules and atoms: 


Molecules and atoms ① are very small in mass and volume ② have the same spacing between each other ③ are always in constant motion ④ The same kind of molecules (or atoms) have the same properties, different kinds of molecules (or atoms) have different properties ⑤ have the meaning of type and quantity ① molecules are the smallest to maintain the chemical properties of substances ① atoms are the smallest particles in chemical changes. 


Atoms can not be divided, not different ② in chemical reactions, molecules can be divided into atoms, can be changed into other atoms and atoms can be recombined into a new molecule ③ atoms can be formed directly into material can be directly formed into material atoms → molecular linkage material molecule and the constituent of this molecule atom compared, the atom is smaller than the molecule, But not all atoms are smaller than commentons, and different kinds of molecules and atoms can't be compared. 


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