The basic knowledge of chemistry in the second year of junior high school, and the second volume of

You kid can't copy it all.

11. The meaning and writing of chemical symbols: (1) The meaning of chemical symbols: AElement Symbol: Represents an element; Represents one atom of the element. B Chemical formula: point 5 (1) sub-point c of this knowledge point

Does anyone have a study question for the three modernizations of junior high school? The exam is coming up next week, and I'm looking for chemistry question types, thanks to all the big brothers and aunts!!

The second year of junior high school is the basic knowledge of chemistry.

The main thing is to back more than 30 kinds of elements that are commonly used, and then back the common ion symbols, and then back the valency, and then back the solubility of common substances, as well as their physical properties and chemical properties.

Now that these are clear, you can start to memorize the equations, as well as the mechanism of the reaction.

The textbook is the most basic, and then do the exercises, don't always do one type of questions, don't always do the questions that examine a knowledge point.

Develop an interest, persevere, and keep learning even if you don't start well.

Chemistry in the second year of junior high school??? I don't know where you are and which version of the textbook you are studying, but in the second year of junior high school, you must have just started to learn chemistry, focusing on cultivating interest, and interest is the best teacher. Come on!!

Substances composed of ions (junior high school) Properties of Fe3O4 (ferric tetroxide) particles (not ions):

1. The particles that can maintain the chemical properties of substances are molecules.

2. The smallest particle in a chemical change is an electron.

3. The positively charged particle is a proton.

4. The non-electrically active particles are molecules, atoms, and neutrons.

5. The particle with the smallest mass is the electron.

6. The equal number of particles in the same atom are protons and electrons.

7. The particles that determine the mass of an atom are mainly the nucleus.

Similarities, differences and connections of sodium ions in the nucleus of sodium:

Commonality: The number of protons in the nucleus is the same.

Differences: The number of electrons outside the nucleus is different.

Connection: is the same element.

The elementary particles that make up atoms are: protons, neutrons, electrons (if there are 3 empty), nucleus electrons (if there are 2 empty).

Among the following substances, the one that is directly composed of atoms is --be--- the molecules are --ad, and the ions are --c---

a, oxygen b, diamond c, sodium chloride d, sulfur dioxide e, charcoal.

Electrons, nuclei (neutrons, protons, etc.).

b aed c