In junior high school, chemistry must memorize key knowledge points, and junior high school chemistr

Names and symbols of common elements and atomic groups: o, oxygen, hydrogen, nitrogen, chlorine, c, carbon, phosphorus, s, sulfur metal: k, potassium, ca, calcium, na, sodium, mg, magnesium, al, aluminum, zn, fe, iron, cu, copper, hg, mercury, ag.

But if you want to understand and truly enter this new world, you have to put in a certain amount of effort. Junior high school chemistry is a stepping stone for high school chemistry, and if you can easily learn chemistry in high school, then you must lay a solid foundation in junior high school chemistry.

Particles that make up matter: molecules, atoms, and other particles.

Changes in matter and properties, physical changes: There is no change in the formation of new matter. No new matter is formed macroscopically, and no new molecules are formed on the microscopic level.

1. CO2 (CO): Passing the gas through the hot copper oxide.

2. CO (CO2): through a sufficient amount of sodium hydroxide solution.

3. H2 (water vapor): through concentrated sulfuric acid through sodium hydroxide solids.

4. Cuo (Cu): Burning the mixture in air (in the oxygen stream).

5. Cu (Fe): add sufficient amount of dilute sulfuric acid.

6. Cu (Cuo): Add sufficient amount of dilute sulfuric acid.

7. FeSO4 (CuSO4): add a sufficient amount of iron powder.

8. NaCl (Na2CO3): add sufficient amount of hydrochloric acid.

9. NaCl (Na2SO4): add sufficient amount of barium chloride solution.

10. NaCl (NaOH): add sufficient hydrochloric acid.

11. NaOH (Na2CO3): add sufficient calcium hydroxide solution.

12. NaCl (CuSO4): add sufficient amount of barium hydroxide solution.

13. Nano3 (NaCl): add a sufficient amount of silver nitrate solution.

14. NaCl (KNO3): evaporation solvent.

15. Kno3 (NaCl): cooling hot saturated solution.

16. CO2 (water vapor): through concentrated sulfuric acid.

1. The most abundant metal element in the earth's crust is aluminum.

2. The most abundant non-metallic element in the earth's crust is oxygen.

3. The most abundant substance in the air is nitrogen.

4. The hardest substance that exists naturally is diamond.

5. The simplest organic matter is methane.

6. The most active metal in the metal activity sequence table is potassium.

7. The oxide with the smallest relative molecular mass is water.

8. The gas with the least density under the same conditions is hydrogen.

9. The metal with the strongest electrical conductivity is silver.

10. The atom with the smallest relative atomic mass is hydrogen.

11. The metal with the smallest melting point is mercury.

12. The most abundant element in the human body is oxygen.

13. The element with the largest variety of constituent compounds is carbon.

14. The most widely used metal in daily life is iron.

1. Liquid oxygen is light blue.

2. Sulfur burns in the air with a faint light blue flame.

3. Hydrogen burns in the air with a light blue flame.

1. The lower end of the funnel is close to the inner wall of the beaker;

2. The end of the glass rod is lightly leaned against the three layers of filter paper;

3. The edge of the beaker containing the filtrate is close to the glass holder for drainage.

1. Common elemental valence formulas:

monovalent potassium hydrochloride sodium silver; divalent oxygen, calcium, barium, magnesium, zinc; trivalent aluminum of tripentanitrogen and phosphorus; copper mercury 12 iron 23; II, tetra, hexasulfur, tetravalent carbon; Many elements have valence, and the valence varies according to different conditions.

2. Common atomic cluster (root) chemical valence formula:

Monovalent hydroxide nitrate; divalent carbonate sulfate; trivalent common phosphate; Usually the negative valence is except for the ammonium root.

3. Proficient in dictating the commonly used valencies of common elements.

1 valence: K, Na, H, Ag, NH4 2 valence: Ca2, Ba2, Mg2, Zn2, Cu2, Hg2, SubFe2

3 valence::Fe3,Al3

1 valence: CL, OH, NO3

2 Valent: O2, S2, CO32, SO42 3 Valent: :p O43

There are many knowledge points that must be memorized in junior high school chemistry. Chemistry is a natural science that studies the properties, composition, structure, changes, uses, preparation methods, and laws of material changes.

Chemistry is closely related to industry, agriculture, daily life, medicine, materials, etc. For example, coal, oil and natural gas are burned to produce carbon dioxide and other substances.

The object of chemical research deals with the interrelationships between matter, or between matter and energy. Traditional chemistry is often about the contact and change of two substances, i.e., a chemical reaction, or the process by which one substance becomes another.

These changes sometimes require the use of electromagnetic waves, which are responsible for initiating chemical reactions. Sometimes, though, chemistry doesn't have to be about reactions between substances. Spectroscopy is the study of the relationships between matter and light, and these relationships do not involve chemical reactions.

1. The three types of particles that make up matter are: molecules, atoms, and ions.

2. Three reducing agents commonly used in reducing copper oxide: hydrogen, carbon monoxide and carbon.

3. Hydrogen as a fuel has three advantages: abundant resources, high calorific value, and the product after combustion is water that does not pollute the environment.

4. There are generally three kinds of particles that make up atoms: protons, neutrons, and electrons.

5. There are only three kinds of ferrous metals: iron, manganese, and chromium.

6. There are three types of fire extinguishers commonly used: foam fire extinguisher, dry powder fire extinguisher, and liquid carbon dioxide fire extinguisher.

7. The flame of the alcohol lamp is divided into three parts: the outer flame, the inner flame and the flame center, among which the outer flame has the highest temperature.

8. The harm of air pollution: it seriously damages human health, affects the growth of crops, and destroys the ecological balance. Global warming, ozone layer depletion and acid rain, etc.

Protection: Strengthen air quality monitoring, improve environmental conditions, use clean energy, factory exhaust gas can only be discharged after treatment, and actively plant trees, afforestation, grass planting, etc.

9. The purification effect of water from low to high is static, adsorption, filtration, and distillation (all physical methods), among which the best operation with the purification effect is distillation, and the water purification agent with both filtration and adsorption is activated carbon.

10. **: Combustibles are rapidly burning in a limited space, and the gas volume expands rapidly. All mixtures of flammable gases, vapors of flammable liquids, and mixtures of combustible dust and air (or oxygen) can occur when exposed to fire**.

1) The meaning of the chemical formula.

Macro implications. a.denotes a substance;

b.indicates the elemental composition of the substance;

Micro significance. a.represents a molecule of the substance;

b.indicates the molecular composition of the substance;

The meaning of the quantity. a.Represents the ratio of the number of atoms in a molecule of a substance;

b.Indicates the mass ratio of the elements that make up the substance.

2) Reading and writing of elemental chemical formulas.

Directly represented by the element symbol:

a.Elemental metals. Such as: potassium K, copper Cu, silver AG, etc.;

b.Solid non-metallic. Such as: carbon C, sulfur S, phosphorus P, etc.

c.Noble gas. Such as: helium (gas) HE, neon (gas) NE, argon (gas) AR, etc.

Polyatoms make up the elemental nature of the molecule: its molecule is composed of several atoms of the same kind, just write a few in the lower right corner of the element symbol.

For example, if each oxygen molecule is composed of 2 oxygen atoms, then the chemical formula of oxygen is O2

Diatomic molecule elemental chemical formula: O2 (oxygen), N2 (nitrogen), H2 (hydrogen), F2 (fluorine), Cl2 (chlorine), BR2 (liquid bromine).

Polyatomic molecule elemental chemical formula: ozone O3, etc.

3) Compound chemistry answer type of slow resistance reading and writing: read first and then write, and read first when written.

Compounds composed of two elements: read as "a certain chemical", such as: MGO (magnesium oxide), NaCl (sodium chloride).

Acids are composed of metallic elements'Compounds: read as "a certain acid", such as: KMno4 (potassium permanganate), K2mnO4 (potassium manganate), MGSO4 (magnesium sulfate), CACO3 (calcium carbonate).

4) Judge the valency of the element according to the chemical formula, and write the chemical formula of the compound according to the valency of the element:

The basis for judging the valency of an element is: the algebraic sum of positive and negative valency in the compound is zero.

Steps to write a chemical formula based on the valency of an element:

a.According to the elemental valence, write out the element symbol and mark the valence;

b.See if the valence of the element has a divisibility and is reduced to the simplest ratio;

c.Cross-inversion writes the valency that has been reduced to the simplest ratio in the lower right corner of the element symbol.

1.Chemical Change: The formation of a change in other substances.

2.Physical Changes: No changes in the formation of other matter.

3.Physical properties: properties that can be exhibited without chemical changes, such as: color, state, density, odor, melting point, boiling point, hardness, water solubility, etc.

4.Chemical properties: the properties of substances exhibited in the changes of chemical Herminor, such as: flammability, combustion, oxidation, reduction, acidity and alkalinity, stability and so on.

5.Commonly used instruments and how to use them.

1) Instruments for heating – test tubes, beakers, evaporation dishes, incendiary spoons.

2) Measuring container - graduated cylinder (the line of sight is kept level with the lowest point of the liquid concave level in the graduated cylinder).

3) Weighing device - pallet balance (left object right yard).

4) Heating utensils – alcohol lamps.

5) Instruments for separating substances and adding liquid - funnel, long neck funnel, separating funnel.

Periodic table, order of metal activity, four major reactions, typical elemental properties.