In the third year of junior high school this year, chemistry is two units behind, what is the best w

The third year of junior high chemistry is just getting started, and the main thing is the principle of back reaction, chemical formula, and eighteen short-period elements. Use the reaction principle to deduce the reactants, products and other properties and relationships between them. Then if you don't understand, just ask, the questions are not difficult, and you really want to figure it out.

That's how I learned in junior high school, and my chemistry grades were always in the top three in the school.

Borrow notes from classmates to make up for the content you have left behind, go out less after class, read books, ask classmates if you don't understand, preview and review is very important, don't do homework because you are lazy, you have to memorize what you should memorize. You must know that there are no stupid students, only students who don't work hard. You don't look at people with good grades who don't do anything on the surface, but in fact they don't do well because they're smart, they actually work hard.

You must have this feeling, in the first and second years of junior high school, the students who are not as good as you have become top students one by one, they all have a commonality, they are all very hard-working, and this is how the top students in our class are cultivated.

I read it myself first, I haven't learned it, I can't ask the teacher quickly, use my spare time to make up for it, I can't keep up with the step, so I have to make it up quickly.

Students in the third year of junior high school should memorize at least the first 20 elements of the periodic table, and then know the valency of common elements, and be able to write the chemical formulas of common substances.

Read all the books first, and do this teaching ginseng. Basically, there is no problem.

Chemistry memorizes, watches, and practices more to learn well, take a look at this, if you don't read chemistry much, especially in junior high school, it's all about memory, and it's hard for you to pass.

Lecture 3: Water in Nature.

1. The composition of water.

1) Water electrolysis experiment: the gas obtained from the positive electrode can rekindle the wooden strip with sparks, which is oxygen; The gas obtained by the negative electrode is capable of combustion, producing a light blue flame, which is hydrogen, which has a volume ratio of 1:2 and a mass ratio of 8:1.

2) Chemical equations.

3) From the electrolysis of water, it can be seen that water is composed of hydrogen and oxygen.

2. Purification of water.

1) Natural water such as river water, lake water, well water, and seawater in nature is not pure water, and contains many soluble and insoluble impurities, all of which belong to mixtures.

2) Natural water can be purified to different degrees through different ways such as precipitation, filtration, adsorption, and distillation.

3) Water is divided into hard water and soft water.

Water containing more soluble calcium and magnesium compounds is called hard water; Water that contains no or little soluble calcium-magnesium compounds is called soft water.

Soapy water can be used to distinguish between hard and soft water. Water that produces more foam is soft water, and water that produces less foam and is prone to scum is hard water.

The use of hard water can bring many troubles to life and production. Laundry is not clean, hardened, boilers waste fuel, damage and overheat**.

Hard water softens. Distill, boil.

3. Take care of water resources.

1) The earth's water reserves are abundant, but the available freshwater resources are limited.

2) Save water and prevent water pollution (from the three aspects of industry, agriculture and life).

4. Composition and composition of matter.

1) Material composition. Mixtures, purities (elemental, compounds).

2) Composition of matter (the particles that make up matter include molecules, atoms, etc.).

A molecule is the smallest particle that maintains the chemical properties of a substance; The mass and volume of the molecule are very small, the molecule is constantly moving, and there is a certain interval between the molecules; Atoms are the smallest particles in chemical change; The essential difference between molecules and atoms: in chemical changes, molecules can be redivided, but atoms cannot be redivided. (For example, in the water electrolysis experiment, water molecules can be divided into hydrogen atoms and oxygen atoms, while hydrogen atoms and oxygen atoms cannot be redivided, but only recombined into hydrogen molecules and oxygen molecules.) ）

Read the book by yourself, and if you can't understand it, ask the teacher or look up the method on the Internet.

I'm about to enter the third year of junior high school, and I'm worried that chemistry is not good, do you have any tips for learning chemistry? In fact, chemistry is still a relatively easy subject to learn, it is relatively easier than physics, as long as you listen carefully in class, actively complete the teacher's homework, teacher, do the experiment carefully after class, do it yourself, and there are some chemical formulas, memorize it, it should be easy.

In fact, learning chemistry is very simple, that is, you must remember more and listen to the teacher's lectures, think carefully and take notes, and then for some special questions, you should also write down in your notebook and practice more, in fact, chemistry is much simpler than physics, as long as you are good at mathematics, chemistry will be able to learn well.

First of all, interest is the best teacher, we live in a world of countless elements, all of which involve chemistry, and chemistry is inseparable from understanding the objective world.

Secondly, starting from the periodic table, to understand chemical knowledge, learn chemical knowledge, know their chemical formulas, this should be remembered, junior high school is in the era of memory rise, more memorization and more memorization will be of great benefit to you in high school and even college and into the society, know the elements, and then further understand the compounds composed of elements, combined with your life practice to understand them. The laboratory experiment will make you refreshed, so it is not difficult to chemistry naturally, and you have unconsciously digested a lot of knowledge, which is a personal experience.

For example, the salt you eat at home is mainly sodium chloride (NaCl), the vinegar is mainly acetic acid (CH3COOH), and the stones, gravel, and soil outside, mainly calcium carbonate, are poured a little bit with acetic acid to bubble, isn't it interesting? It's a chemistry in a lab.

First of all, congratulations on your upcoming junior high school year. A new subject is about to be opened to teach chemistry. You have such worries.

It shows that you are a very serious person. Chemistry is not that difficult, the first step is to memorize it from the periodic table. I memorized her very well.

Then out of chemistry. Actually, it's just those experiments. You memorize it.

It's okay to draw inferences.

The most important way is to memorize more chemical elements and chemical formulas, memorize the most basic things clearly, and then rely on your own understanding to do more questions, so that you can learn chemistry well.

You can listen carefully in class, ask questions if you have any questions, pay attention to take good notes, and do more relevant exercises. I'm sure I'll improve my chemistry grades.

You can preview it in advance, and then just review it, and if you're interested in chemistry, you'll learn it faster.

Chemistry is a compulsory subject in secondary school, and if you want to improve your chemistry scores, you need to memorize the chemical equations. When you first start learning the subject of chemistry, the knowledge you are exposed to is basically relatively shallow knowledge, which means that at this time, as long as you are willing to spend corresponding efforts, then you can master this knowledge. I hope that everyone can face it with the right attitude when studying chemistry, and be able to use the right way to do a good job in their own psychological construction, which is very meaningful.

When entering the study of chemistry, parents should let their children write down all the symbols of chemistry, because the special element symbols of chemistry are very important. And no matter what stage you reach in the future, these elemental symbols will need to be used, so memorizing these elemental symbols is the most important way to behave, and it will also enable students to achieve better results.

In addition to these, parents can also choose to let their children know more about chemical equations at this time, because children's understanding of chemical equations is also very meaningful. Once you understand the chemical equation, you will know some of the variables in the equation, and you will also know what kind of changes will occur when two objects react together, and what kind of new substances can be generated. In this process, a series of elemental knowledge such as valency also need to be memorized, and after remembering these things, the child's personal performance will be improved.

College itself is not a particularly difficult subject, but students must remember the twists and turns in chemistry, only by memorizing these things completely, children can use better grades. That is to say, when studying chemistry, students should spend all their minds and learn as much as possible about all the new things they are exposed to, so that they can use a better way to get higher scores when facing chemistry in the future.

You can let your child do more chemistry experiments, memorize more chemical formulas, chemical elements, and let your child brush more chemistry questions, so as to improve your child's chemistry score.

To improve children's learning ability, it is necessary to formulate a strict study plan for children, let children do a good job of pre-studying, and listen carefully in class.

The first step to improve chemistry scores is to make children interested in nature and cultivate interest. Take him to do all kinds of experiments and feel the magic of chemistry.

Let your child know more about chemistry, read some chemistry books, and enroll your child in a chemistry class.

I was 3 at the beginning of last year, there was a big gap in the level of chemistry in the class, because chemistry was a beginner so at the beginning was simple and good, but some people also found it difficult to accept, according to my summary, you should pay more attention to the ion part, the difficult part is this, use more ions to see the problem!

I also agree with memorizing the properties of matter and equations, and finding out the laws from the equations, so that I can also write.

Imagine how much fun chemistry is to learn and play at the same time.

Chemistry in the third year of junior high school is to memorize, nothing else. If you don't learn well in the third year of junior high school, then you should listen to the book of organic chemistry in high school. Do more practice on a regular basis.

Memorize the first 20 elements of the periodic table, valence, and the state of the product after the reaction, and don't memorize it by rote.

In fact, chemistry in junior high school is very simple, you just need to memorize the equations in the books, the knowledge points, and the properties of some substances. High school is where it really begins.

Hello landlord, I'm a junior in high school. My best subject is chemistry. Chemistry is an experiment-based subject, and it is inevitable that something must be memorized. As long as you can do the following things in junior high school chemistry, you can be OK.

1.Reading. Look at the experiments on the book. Look at every detail and think about the principle clearly. You can ask yourself what chemicals you can use if you want to get dry CO2 and why (concentrated sulfuric acid, sodium hydroxide powder, etc.).

2.Write chemical equations. When I was in class, our teacher told us to write chemical equations in class, and they wrote them in books, even though they were ready-made. It is necessary to write several times to form a habit, which will help solve the problem.

3.Observe the periodic table. The arrangement of elements in the periodic table follows a certain law, how the properties of the elements of the same family or the same period change, ask yourself. At this time, there will be a lot of questions, find the teacher to answer, the impact will be deep, and the effect will be very good.

In addition, it is analogous to law chemistry. For example, if sodium reacts with water to release hydrogen, the chemical equation for the reaction of potassium and water can be directly derived.

Because sodium and potassium are in the same group of the periodic table. It can also be inferred from potassium in the next cycle of sodium that potassium has strong reducibility and reacts more violently with water.

4.Write more questions and read the example questions in the exercise book. Good at using the idea of conservation to solve problems.

1. Take good notes 2. Listen carefully 3. Junior high school chemistry is not difficult, as long as you learn it, you can pass it, and you will be excellent in hard work.

Personally, I think it's very simple. In junior high school, it is just memorization, chemical equations and periodic tables have to be memorized. The chemical valence of a chemical element. Then I do more questions, and I feel that chemistry in the middle and high school entrance examinations is all basic questions. It's okay to study well and listen to good lectures.

What you have to do now is to make reasonable use of your time, and not be arrogant and impatient to thoroughly read your textbooks first, otherwise, it will be impossible to improve later. Do a good job in each question, take good notes, summarize the problem, even if it is a small problem that cannot be solved, you must ask the teacher and classmates, and learn to draw inferences. Memorization involves every point of our knowledge, and finds out the difficulties, doubts, and key points.

When you grasp your foundation, buy a five-year high school entrance examination three-year simulation to strengthen your knowledge points, and on the premise of a solid foundation, do the first document of the high school entrance examination, or 38 sets of Tianli, to improve your overall knowledge points. Of course, you can't blindly study hard, you have to give yourself a study plan, persevere, and calculate how much you can improve according to your daily progress.

Secondly, a copy of the study plan is attached:

1: Make your own study plan in advance.

2: Review, preview, summarize, and take notes in advance.

3: Familiar with every knowledge point we are involved in, ask if you don't understand, do more, practice more.

4: Do a good job in each question, summarize it, and learn to draw inferences.

5: Change from passive to active follow-up every time.

If you don't understand something, even if it's very simple, you have to understand it, and you must not be embarrassed to ask teachers or classmates because it's simple.

Cultivate interest in memorizing reaction equations and experiments.