化学复习（Chemical review）.doc

化学复习（Chemical review） Atoms are composed of protons, neutrons and electrons, but they have no neutrons in their nuclei. There is also a different combination of the same element in the same substance, such as Fe304 (Fe: + 2, + 3), NH4N03 (N: -3, + 5). 3. Although the material species are different, the relative molecular weight is the same. Such as CO and N2, H3P04 and H2SO4, NaHCO3 and MgC03, (NH4) 2HP04 and (NH4) 2S04, etc. 4. The protons and the electrons are the same particles, not necessarily the atoms of the same element. (1) it could be two different molecules, such as H2O and NH3; (2) it could be different atoms and molecules. S and 02; (3) it could be two different ions, such as Na + and NH4 +. 5. The metal in front of the metal active sequence table can be replaced by the metal in the back of the metal from their salt solution, but K, Ca, and Na are exceptions. In the soluble salt solution, the K, Ca, and Na are put into the soluble salt solution. They do not react with the salt directly, but instead react with the water first, and the resulting base reacts with the salt. For example, when you put sodium metal into the solution of CuS04, you have a chemical reaction: 2Na + 2H2O = 2NaOH + H2 up, 2NaOH + CuSO4 = Cu (OH) 2 6. Most common metal elements are solid at normal temperature. Only metal mercury is liquid at normal temperature. 7. The solubility of most substances increases with the increase of temperature, and only a very few materials decrease with the increase of temperature, such as solid Ca (0H) 2 and common gas. The CO2 is usually neither burning nor burning, but the burning magnesium strips can be burned in the C02:2MgO + C. 9. A substance whose mass fraction is a fixed value is not necessarily pure. For example, in the compound NaHC03 and MgC03, the mass fraction of the carbon element is 14.29%, regardless of the combination of the two, the quality score of the carbon element is always determined (14.29%). 10. Combustible combustion requires t