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Mnemonic for valence numbers 1: Fluorine, chlorine, bromine, iodine, and hydrogen have a valence of 1; likewise, metals such as potassium, sodium, and silver do as well. Barium, calcium, magnesium, zinc oxides in the divalent form; aluminum and silicon in the trivalent and tetravalent forms remain constant. Be careful with the valence of chlorine and nitrogen: copper and mercury are 1 and 2, while gold is 3. 24-carbon lead, 23-iron; 246-sulfur, 35-phosphorus. Mnemonic for the main oxidation states of common elements 2: Fluorine, chlorine, bromine, and iodine have an oxidation state of –1 ； Ortho-hydrogen silver and potassium sodium. Remember oxygen’s negative two first ； Dihydrate magnesium calcium barium and zinc. Ortho-tri is aluminum ortho-tetrasilicon ； Let’s assign the variable value again below. All metals are in the positive valence state ； One or two copper, then two or three iron. Manganese ortho-two-four and six-seven ； Remember carbon 2 and 4. Non-metallic negative major positive asymmetry ； Chlorine: negative one, positive one, five hundred seventy. Nitrogen phosphorus negative three and positive five ； Different phosphorus triazotetra. Sulfur has -2, +4, +6 ； You’ll get proficient by using it while learning. Mnemonic for valence numbers 3: Hydrogen, chlorine, potassium, sodium, silver have a valence of 1 ； Divalent calcium, barium, magnesium, zinc oxide; trivalent aluminum, silicon, nitrogen, phosphorus ； Two-three iron, two-four carbon; two-four-six sulfur, all present ； Copper is most commonly in the +2 valence state. Common mnemonics for root ion prices: Monovalent ammonium and nitrate ions ； Hydrohalide hydroxide. permanganate chlorate ； Perchlorate acetate. Divalent sulfate carbonate ； Manganese hydrogen sulfate. Temporarily consider ammonium as having a positive charge ； Negative three has one phosphate group. Metal activity series: (Middle school) Potassium, calcium, sodium, magnesium, aluminum; zinc, iron, tin, lead, hydrogen; copper, mercury, silver, platinum, gold. (High school) Potassium, calcium, sodium, magnesium, aluminum, manganese, zinc, chromium, iron, nickel, tin, lead, hydrogen ； Copper, mercury, silver, platinum. Solubility of salts: Potassium, sodium, ammonium, and nitrate salts are soluble; hydrochloride salts and silver mercurite are insoluble ； Barium and lead are insoluble in sulfates, while phosphocarbons are generally insoluble. Most acids are soluble while alkalis are less soluble; only potassium, sodium, ammonium, and barium are soluble. Mnemonic for the common element valences (1): Potassium, sodium, hydrogen, and silver have a valence of +1; calcium, magnesium, zinc, and barium have a valence of +2 ； Fluorine, chlorine, bromine, and iodine have a negative one-valence, while oxygen usually has a negative two-valence ； Copper has +1 and +2 states, aluminum has +3, while iron has +2 and +3 states ； Carbon has +2 and +4, while sulfur has -2, +4, and +6. Mnemonic for the valence of common elements (II): Hydrogen, lithium, potassium, sodium, and silver have a valence of +1; oxygen, magnesium, calcium, barium, and zinc have a valence of +2. Copper and mercury have valences of +1 and +2, while iron has valences of +2 and +3. Carbon, tin, and lead have valences of +2 and +4. Sulfur has valences of -2, +4, and +6; nitrogen and phosphorus have valences from -3 to +5. The halogens have valences of -1, -1, +3, +5, and +7. Remember that boron, aluminum, and gold have a valence of +3. Mnemonic for oxygen production: manganese dioxide, potassium chlorate ； Mix well and add heat. Oxygen generation devices have their own characteristics ； The base is high while the mouth is low, with a slight tilt. Mnemonic for gas collection: Use the exhaust method when interacting with water ； Determine the upper and lower limits based on density. Insoluble/low-solubility wastewater treatment method ； The purity of the resulting gas is high. Mnemonic for electrolyzing water: Positive oxygen ions are small and can aid combustion ； Negative hydrogen can burn with great intensity. Mnemonic for the solubility of common substances (1): Potassium, sodium, and nitrates are soluble; (Potassium salts, sodium salts, and nitrates all dissolve in water.) ) Mercurous(II) chloride removal with hydrochloric acid; all salts, except silver chloride and mercurous chloride, are soluble in hydrochloric acid. ) As for sulfates, barium and lead are not allowed to be present; (the substances insoluble in sulfates are barium sulfate and lead sulfate. ) The other types of salts, namely carbonates, sulfites, phosphates, silicates, and sulfides, dissolve only potassium, sodium, and ammonium – only the corresponding potassium salts, sodium salts, and ammonium salts are soluble. Finally, as for bases, there are potassium, sodium, ammonium, and barium. (Soluble in potassium hydroxide, sodium hydroxide, barium hydroxide, and ammonia water.) ) Mnemonic for the solubility of substances (II): Potassium, sodium, ammonium salts and nitrates dissolve completely without difficulty; mercury(II) chloride, silver chloride, barium sulfate, and lead sulfate do not dissolve easily. Remember the formation of precipitates: hydrogen sulfates and alkalis, carbonates, phosphates, nitrates; only potassium, sodium, and ammonium are soluble.