Who has knowledge of chemistry and physics in the third year of junior high school? Thank you

Go to the library and look for it, there will definitely be what you are looking for.

1. Chemical change: the change of other substances is generated.

2. Physical change: no change in other substances.

3. Physical properties: properties that do not need to undergo chemical changes, such as: color, state, density, odor, melting point, boiling point, hardness, water solubility, etc.

4. Ions. 1) Concept: Charged atoms or clusters of atoms.

2) Representation method and significance: such as Fe3+: one iron ion with 3 units of positive charge.

5. Elements. 1) Concept: A general term for a class of atoms with the same number of nuclear charges (protons).

2) The number of protons determines the type of element.

3) The chemical properties of an element are closely related to the number of electrons in the outermost shell of an atom.

6. The law of conservation of mass.

1) Concept (reactants and products do not change in mass before and after).

2) Cause (three invariants - the type, number, and mass of atoms do not change before and after the reaction).

3) Calculations related to chemical equations.

Note: The law of conservation of mass only applies to chemical changes, not to physical changes.

The mass of a substance that does not participate in the reaction and the mass of a substance that is not a product cannot be counted in the "sum".

Consider whether a substance in the air participates in the reaction or if a substance (e.g. gas) is missing.

7. Preparation method of carbon dioxide.

1) Laboratory preparation of carbon dioxide.

Principle: Reaction with limestone and dilute hydrochloric acid:

CaCO3+2HCl==CaCl2+H2O+CO2 Solid-liquid non-heating device is selected.

Gas collection method: upward air exhaust method.

Verification method: The prepared gas is passed into the clarified lime water, and if it can become turbid, it is carbon dioxide.

Full inspection method: Use a lit wooden strip and put it at the mouth of the gas collection bottle, and the wooden strip is extinguished. is already full of carbon dioxide.

2) Industrial production method of carbon dioxide:

Calcined limestone: caCO3 high temperature cao + CO2 quicklime and water reaction can obtain hydrated lime: cao + h2o = ca(oh)28, solubility table memory formula.

Potassium sodium ammonium salts are all soluble, and nitrates are the same.

Alkali dissolves ammonium, potassium, sodium, barium calcium, sulfates, and barium calcium.

Chloride except silver mercurous, carbon phosphate is mostly insoluble.

1 Acid + Metal = Salt + Hydrogen.

Reaction conditions: Acids can not be used with strong oxidizing acids, such as nitric acid, concentrated sulfuric acid, (commonly used dilute sulfuric acid, hydrochloric acid) Metals must be located before hydrogen (commonly used Mg, Al, Zn, Fe) Replacement reaction with iron to form ferrous salts (iron element + 2 valence) (1) Magnesium and hydrochloric acid reaction: mg + 2HCl = = mgCl2 + H2

Phenomenon: Bubbles are formed on the surface of the metal, and the metal is gradually dissolved. (2) Aluminum reacts with hydrochloric acid 2Al+6 HCl== 2AlCl3

pwd=1234 Extraction code: 1234 Introduction: High-quality materials for junior high school chemistry**, suitable for teachers at all stages, daily tutoring for students, sprint for the high school entrance examination, and skill improvement learning.

Physics knowledge points: mainly divided into four parts. The first part is mechanics and acoustics, which accounts for 40 points in the high school entrance examination.

Mechanics mainly includes the basic knowledge of measurement, density and mass, buoyancy, gravity, pressure, support force, friction. After that, it comes to the knowledge of work and energy, i.e., the work done by an object, the work and the power. Simple mechanical, mechanical efficiency.

These knowledge points are interrelated and co-systematic. It is the more difficult part of junior high school physics. Regarding acoustics, the knowledge is relatively simple, but it is only the three elements of sound, which needs to be paid attention to.

The second part is electricity, which accounts for 35 points in junior high school physics, and this part of the score is easier to get, mainly because of the memorization and mastery of some formulas, including: current, voltage, resistance, electrical work, electric power and other related knowledge. The third part is optics, which accounts for 10 points in the high school entrance examination, involving the propagation, reflection, refraction, and lens of light, and this part focuses on the practical application of knowledge.

The fourth part is thermal, which is relatively simple in the high school entrance examination, but accounts for 15 points, mainly the heat absorption and release between the changes in the state of matter and the corresponding titles: vaporization, liquefaction, melting, sublimation, condensation, after understanding and memorizing these points, plus a calorific value formula, thermal science is not much difficult. Junior high school physics is still relatively simple, as long as the corresponding formulas are proficient and do more exercises, the high school entrance examination is not a big problem at about 90 points.

It's better for you to read the book and summarize it yourself.,Read it and write it and you'll remember it.,Don't say all of this.,I don't think it's too good.。

Physics is just a few formulas, chemistry commonly used elements are more than a dozen, the question comes out to make these together and there is an answer, the third year of junior high school physics and chemistry comprehensive paper I never answer the question for more than 1 hour, generally the first single subject in the class, you can remember a lot of songs, but you can't remember dozens of letters, I don't understand.

I am a first-year high school student and have a deep understanding of the high school entrance examination. To review physical chemistry, we must first consolidate the knowledge in the books, and sometimes the topics are often in the textbooks, so we should pay attention to the steps of those experiments in the books. Secondly, you should take out the test papers you have done and look at them, and think about why you were wrong

When the high school entrance examination is approaching, you don't have to be nervous, just follow the "three steps" to review step by step. Good luck with your exams.

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Is it okay to bother to be more detailed?