1. Listen carefully in class. Generally, teachers will give ways to remember things that are difficult to remember, and try to remember some of them in class.

2. When doing homework, don't always open the book or notebook to do it. Either read it before doing it, or take notes after doing it. Otherwise, remember the answers before doing it on the test paper.

3. If there are any problems that you can't solve in your homework, make a mark and wait for the teacher to comment or take the initiative to ask the next day.

You don't need to spend a lot of time memorizing the knowledge points of chemistry in Grade Three. Only the usual homework can be done by yourself, instead of always copying books or notes or other people's homework.

Quick score extraction method:

1. Solve the chemical equation

First, start with the valence of elements, find a formula and recite it. After figuring out some commonly tested details, such as the bivalence generated by iron replacement reaction

, then recite more important chemical equations, make oxygen to make carbon dioxide (dead back), and commonly use acid-base neutralization reactions, etc. (These should not be difficult, If you can't, you can ask the teacher to find out the principle. After writing, check whether the balance is unreasonable, etc.

2. Calculation method < P > Set an unknown number that you think is convenient to calculate as X (if you require a mass score and your foundation is poor, it is recommended to set the mass of the reacted substance now, and then ask, To be on the safe side)

The topic definitely gives the complete reaction mass of the generated gas, precipitate or reactant product (it must be completely reacted), and calculates the relative molecular mass (including unknown quantity and known quantity) of these substances. Available:

(relative molecular mass of unknown quantity)/x = (relative molecular mass of known quantity)/known mass of corresponding substance

3. Difficulties

Generally speaking, chemical calculation problems are not difficult, and the difficulties must lie in letting you calculate the mass fraction of a solution after the reaction, etc. The remaining solute mass of the solution has generally been worked out, so the solution quality must be thought clearly, and precipitation and gas must be reduced. If you add xx grams of water and xxx grams of anything, just add these to the quality of the solution at the beginning and subtract the precipitated gas at the end, and there will be no problem in general.

Daily accumulation methods:

1. Difficult before easy

Focus on your own learning situation, first highlight the subjects you find difficult, spend more time solving difficult problems and break through your weaknesses.

2. Reading and practicing every day

Pay attention to the interval between arts and sciences, interspersed with review. Generally, there are many calculations in science and more recitations in liberal arts. Different parts of the human brain have their own special functions. To arrange the review time, there should be a period of calculation practice, a period of memorization and an analysis experiment, so that different areas of the brain can work and rest in turn, which can improve the excitement of the brain, activate thinking and enhance memory.

3. There should be two or three stages of review for each subject.

In the first stage, the textbook should be reviewed comprehensively and systematically, and the knowledge system network of each chapter should be straightened out, so that the brain can have a clear memory of the whole book. In the second paragraph, pay attention to exercise, repeat the exercises that you have practiced once and for all, and repeat the exercises that you are familiar with to deepen your memory; For those who are not very skilled, or even have difficult problems, repeat practice and operation. If time permits, the third paragraph combines browsing memory with strengthening memory. After such a review before the exam, we can achieve the goal of having an open mind, clear thinking and developing our ability.

4. review the past and learn new things. don't do new exercises, let alone study difficult problems.

The topics of each examination paper are designed according to the syllabus and examination syllabus of the textbook, so the types of examination topics are similar to the students' usual exercises. Even the difficult comprehensive analysis questions and comprehensive calculation questions are often the application of knowledge points in several chapters of the textbook. The problem is that these questions often turn around, hiding applicable knowledge points and hiding some conditions for solving problems.

If you memorize the concepts, principles, formulas and practiced topics of textbooks, notes and reference books before the exam, it will be beneficial to associate, draw lessons from, draw analogies and draw inferences.

If you focus on doing new questions before the exam and concentrate on solving difficult problems, you won't be able to memorize them. Still sinking in the "sea of questions", it is not worth the loss.

5. In the process of reading, you should know how to take breaks.

Generally, you should concentrate on reading and practicing, and take a break for 1 minutes in an hour or an hour and a half. It is best to have a dynamic rest, that is, leave your seat, take a walk, sing, move your limbs, wash your face and even do some housework. In this way, the brain is regulated and refreshed, preparing for the next round of reading and practice, and concentrating on the next round of study. 1. Difficult before easy

Focus on your own learning situation, first highlight the subjects that you find difficult, spend more time solving difficult problems, and break through your weaknesses.

summary of junior high school chemistry knowledge points:

1. colors of common substances in junior high school chemistry

(1) colors of solids

1. red solids: copper, iron oxide

2. green solids: basic copper carbonate

3. blue solids: copper hydroxide, copper sulfate crystals

4. purplish black. Diamond

7, silvery white solid: silver, iron, magnesium, aluminum, mercury and other metals

8, black solid: iron powder, charcoal, copper oxide, manganese dioxide, ferroferric oxide, (carbon black, activated carbon)

9, reddish brown solid: iron hydroxide

1, white solid: sodium chloride, activated carbon. Magnesium oxide

(2), color of liquid

11, colorless liquid: water, hydrogen peroxide

12, blue solution: copper sulfate solution, copper chloride solution

13, light green solution: ferrous sulfate solution, ferrous chloride solution, ferrous nitrate solution

14, and yellow solution: ferric sulfate solution. Iron nitrate solution

15, purple-red solution: potassium permanganate solution

16, purple solution: litmus solution

(3), gas color

17, reddish-brown gas: nitrogen dioxide

18, yellow-green gas: chlorine gas

19, colorless gas: oxygen, nitrogen. Most gases, such as hydrogen chloride gas.

II. Junior high school chemistry III

1. Three major chemical processes in ancient China: papermaking, gunpowder making and porcelain burning.

2. Three types of oxidation reactions: explosion, combustion and slow oxidation.

3. Three kinds of particles that make up substances: molecules, atoms and ions.

4.

(2), carbon dioxide is composed of carbon dioxide molecules;

(3) A carbon dioxide molecule is composed of a carbon atom and an oxygen atom.

6. Three kinds of particles that make up atoms: protons, neutrons and electrons.

7. Three causes of water pollution:

(1) The industrial "three wastes" are discharged at will.

(2) Arbitrary discharge of domestic sewage

(3) Arbitrary application of pesticides and fertilizers

8. Three methods of collecting gas: drainage method (water-intolerant gas), upward air discharge method (gas with higher density than air) and downward air discharge method (gas with lower density than air).

9. Three unchanged laws of mass conservation: atom. The atomic mass remains the same.

1. Three methods to change unsaturated solution into saturated solution: increasing solute, reducing solvent and changing temperature (increasing or decreasing).

11. Three conditions whether the metathesis reaction can occur: generating water, gas or precipitation

12. Three chemical fertilizers: N, P and K

13. Discharge. Oxides of sulfur.

14. White light-emitting substances when burned: magnesium bars, charcoal and candles.

15. Flammable and reducing substances: hydrogen, carbon monoxide and elemental carbon.

16. The three flammable gases are: hydrogen (ideal), carbon monoxide (toxic) and methane (commonly used). Petroleum, natural gas. (All are mixtures)

19. Three ferrous metals: iron, manganese and chromium.

2. Three oxides of iron: ferrous oxide, ferric oxide and ferric oxide.

21. Three oxides of iron-making: iron ore, coke and limestone.

22. Strong oxidizability.

24. Three common names of sodium hydroxide: caustic soda, caustic soda and caustic soda.

25. Three oxides generated by the decomposition of basic copper carbonate by heat: copper oxide and water (oxidation