The concept of chemistry in the second year of junior high school, the basic concept of chemistry in

1. Not the same. Water and hydrogen peroxide are two completely different substances, and it can only be said that their constituent elements are the same, but because of the difference in the number of atoms, the properties are very different.

For physical properties, such as charcoal and diamond, they are both carbon elements, but the color, hardness, density, etc. are very different, hydrogen peroxide and water are not the same substance, so the physical properties cannot be exactly the same, but some aspects are the same, such as liquid at room temperature.

For example, many organic substances are compounds of the three elements of carbon, hydrogen and oxygen, but the number of atoms of these three elements is different, and they become a lot of organic matter.

2. It doesn't count. The definition of an ion is an electrically charged atom, which is a separate category and cannot be grouped within an atom. Just like a molecule, a small particle that is then disassembled is an atom, but the atom cannot be classified as a molecule.

1.Molecules are elementary particles that retain the chemical properties of substances, so as long as the molecules are different, the chemical properties of substances are different, whether they are arranged differently or the number is different. Just like you said about the water molecule and the hydrogen peroxide molecule, the hydrogen peroxide molecule has one more oxygen atom, that is, the molecular formula is different, then the chemical properties are of course different.

2.The elementary particles that make up matter are molecules, ions, atoms, and atoms can make up molecules. In this way, atoms and ions should be juxtaposed, not a type of atom.

Unlike a substance composed of molecules, the molecule is the smallest particle that retains its chemical properties, that is to say, its chemical properties are determined by the molecule, so the chemical properties are different. (Hydrogen peroxide splits water and hydrogen, while water does not).

Ions are not atoms, atoms are not charged, ions are formed by atoms after gaining or losing an electron.

1. The atoms that make up the molecule are the same, as long as the number is different, they can also form different molecules, so are the chemical properties of these molecules the same? For example, water molecules and hydrogen peroxide molecules.

A: When we first came into contact with chemistry, we learned that --- molecule is the smallest particle that retains the chemical properties of a substance. That is to say, different molecules have different properties.

So the chemistry of these molecules is different. In your example--- the properties of H2O and H2O2 are very different.

2. Are ions also a type of atom?

Answer: Ions are obtained by the capture or loss of electrons by atoms. Not a type of atom.

1. The chemical properties are determined by molecules, and the physical properties are determined by atoms, so the chemical properties of molecules with the same atoms but different numbers are different.

2. Ions are charged atoms, strictly speaking, they are atoms, but the chemical properties of the two are different, while the physical properties are the same.

(1) Physical change: 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.

It often refers to a change in the state of matter, a change in shape, a shift in position, etc.

For example: the change of the three states of water, the volatilization of gasoline, the sublimation of dry ice, the making of wood into tables and chairs, the breaking of glass, and so on.

(2) Chemical change: There is a change in the formation of new substances, also called chemical reactions.

New substances are formed on the macroscopic level and new molecules are formed on the microscopic level.

Chemical changes are often accompanied by some reaction phenomena, such as luminescence, heat generation, gas production, color change, precipitation, etc. In some cases, reaction phenomena can be used to determine whether a chemical change has occurred or what kind of substance the product is.

(3) Physical properties: the properties of substances that can be exhibited without chemical changes.

Physical properties are not properties that manifest themselves only when matter undergoes physical changes; For example:

Wood has a dense nature and does not require it to change shape before it manifests itself.

The physical properties perceived by the senses mainly include: color, state, smell, etc.

The physical properties that need to be determined by instruments are: melting point, boiling point, density, hardness, dissolution growth, conductivity, etc.

There is no chemistry, which is a subject offered in the ninth grade.

The main subjects in the second year of junior high school are: Chinese, Mathematics, English, Geography, History, Politics, Biology and Physics.

The curriculum that runs through the three years of junior high school includes: Chinese, Mathematics, English, Ethics and the Rule of Law. Physics will be taught in the eighth grade, and Chemistry will be taught in the ninth grade.

Sub-subjects include: Physical Education, **, Fine Arts, Information, etc.

The chemical origin theory divides the origin of life into four stages.

The first stage.

The stage of generating organic small molecules from inorganic small molecules, i.e., the process of chemical evolution of the origin of life, was carried out under primitive terrestrial conditions. It is important to note Miller's simulations. In this experiment, a flask containing an aqueous solution represents the primordial ocean, and its upper spherical space contains a "reducing atmosphere" of hydrogen, ammonia, methane, and water vapor.

When Miller analyzed its chemical composition, it found that it contained a variety of new organic compounds, including 5 amino acids and different organic acids, while also forming cyanogenic acid, which can synthesize adenine, which is the basic unit of nucleotides.

Miller's experiments tried to prove that the first step in the origin of life, the formation of organic small molecules from inorganic small molecules, was entirely possible under the conditions of the primitive earth.

The second stage.

Biological macromolecules are generated from small organic molecules. This process occurs in the primordial ocean, that is, amino acids, nucleotides and other small organic molecules, after long-term accumulation, interaction, under appropriate conditions (such as the adsorption of clay), through condensation or polymerization to form primitive protein molecules and nucleic acid molecules.

The third stage.

A multi-molecular system is composed of biological macromolecular substances. How did this process come about? The former Soviet scholar Obalin put forward the agglomerate hypothesis, and he experimentally showed that when proteins, peptides, nucleic acids, gelatin, gum arabic and polysaccharides are placed in a suitable solution, they can automatically concentrate and aggregate into dispersed globular droplets, which are aggregates.

The fourth stage.

Organic polymolecular systems evolved into primitive life, including the birth of cells marked by the establishment of biochemical and genetic systems. This stage was formed in the primordial ocean and is the most complex and decisive stage in the process of the origin of life. At present, it is not possible to verify this process in the laboratory.

In some places, the curriculum has been changed to learn chemistry in the second year of junior high school, but the content is the same as that of the third year of junior high school.

In the second year of junior high school, some schools offer chemistry courses, which lays a good foundation for learning in the third year of junior high school, which is a good thing.

In some provinces and cities, science also has chemistry content in the second year of junior high school.

There are also those abroad that have chemistry classes in the first year of junior high school.

I only got it when I was in my third year of junior high school.

1. Chemical changes and physical changes.

2. Chemistry and procedures.

3. The concept of the four basic types of reactions.

4. The law of conservation of mass.

5. Atom, proton, neutron, electron and extranuclear electron configuration.

Let the mass of ammonium nitrate be x and the total mass of fertilizer be y

The relative molecular weight of ammonium nitrate is 80, of which the relative molecular mass of nitrogen is 28, so the mass fraction of nitrogen in ammonium nitrate is 28 80=35%, so the mass of nitrogen in ammonium nitrate is 35%x

So 35%x=32%y

So x:y is equal to 32:35

Therefore, the mass fraction of ammonium nitrate is 32 35 * 100% = is there a chemistry course in the second year of junior high school? . .